Turn YouTube Into Your Language School: Language Reactor + Lianki

What if your favorite YouTube channels became your personal language tutors? What if every video you watch could accelerate your language learning? With the right combination of tools, this isn't just possible—it's one of the most effective ways to learn a language.

YouTube is a goldmine for language learners: speaking-oriented videos (vlogs, interviews, podcasts, tutorials) offer clearer, more comprehensible speech than dramatic movie dialogue. Real people speaking directly to camera, explaining concepts, telling stories—this is the sweet spot for language acquisition.

Today I want to introduce you to Language Reactor, a powerful browser extension with over 2 million users, and show you how to supercharge it with Lianki's spaced repetition system for a workflow that makes language learning feel less like studying and more like watching content you already love.

What is Language Reactor?

Language Reactor (formerly "Language Learning with Netflix") is a Chrome extension that transforms video streaming platforms into interactive language learning environments. Think of it as a Swiss Army knife for language learners who want to learn through immersion.

Core Features

Dual Language Subtitles The killer feature: Language Reactor displays subtitles in two languages simultaneously—your native language and the one you're learning. You can instantly connect unfamiliar words and phrases with their translations without pausing the video. You can even blur the target language subtitles to practice listening first, then hover over any word to reveal it.

Pop-up Dictionary & Word Lookup Hover over any word in the subtitles to see an instant definition, pronunciation, and example sentences. Click the word to hear it spoken, and get links to external dictionaries for deeper exploration. Every word in the current video is ranked by frequency and learning stage in a side panel that updates in real-time.

Precision Video Controls Language Reactor adds controls that let you:

Jump between subtitle segments with one click
Loop difficult sentences automatically
Slow down playback without distorting audio
Save specific timestamps for later review

Platform Support The extension works with:

YouTube: Thousands of channels with automatic subtitle support—the best platform for comprehensible input
Netflix & streaming: Full dual-subtitle support for shows and movies
Web content: Import articles and ebooks with machine translation
30+ languages supported: From Spanish and French to Japanese, Korean, Arabic, and beyond

Pro Features (€5.62/month)

The free version gives you the core dual-subtitle and dictionary features. Upgrading to Pro unlocks:

PhrasePump: A built-in spaced repetition system that creates listening exercises from sentences containing your saved vocabulary. It reinforces words you've marked for review while introducing new vocabulary in context.

Vocabulary Export: Export your saved word lists with context and definitions to formats compatible with Anki and other SRS tools. This is where Lianki comes in.

AI Chatbot (Aria): An AI language partner that provides instant corrections, explores endless topics, and helps you build conversational confidence.

Speech Recognition: Practice speaking and get real-time feedback on your pronunciation.

Why Language Reactor is a Game-Changer

Traditional language learning apps often teach vocabulary in isolation—flashcards with single words divorced from any meaningful context. Language Reactor flips this: you learn words embedded in real content, with emotional context, tone, facial expressions, and real-world usage patterns.

Research consistently shows that comprehensible input—content that's mostly understandable with a few new words—is one of the most effective ways to acquire a language. Language Reactor makes finding and consuming comprehensible input effortless:

Find YouTube channels with clear, conversational speech (vlogs, tutorials, interviews)
Learn from speaking-oriented content that's naturally more comprehensible than scripted drama
Watch videos where you understand 70-80% and learn the rest through dual subtitles
Build vocabulary from authentic media, not textbook examples
Learn grammar patterns implicitly by seeing them used naturally

Why YouTube beats movies: YouTubers speak directly to camera with clearer enunciation, repeat key phrases naturally, and explain concepts step-by-step. Compare a vlogger's "Today I'm going to show you how to make pasta" to a mumbled movie line in a noisy restaurant scene. The vlogger wins every time for comprehension.

According to language acquisition research, this kind of immersion-based learning leads to better retention, more natural pronunciation, and faster overall progress compared to traditional study methods.

What Does Lianki Bring to the Table?

Language Reactor solves the input problem—it gives you access to great content with the scaffolding you need to understand it. But understanding something once doesn't mean you'll remember it. That's where Lianki comes in.

Lianki is a modern spaced repetition system built around the FSRS algorithm—the same algorithm now used in Anki 23.10+ and praised for being significantly more accurate than older SM-2 based systems. FSRS uses a sophisticated model of memory (Difficulty, Stability, Retrievability) to schedule reviews at the optimal moment—right before you're about to forget something.

Why Lianki for Video Content?

Unlike traditional flashcard apps, Lianki is designed for content-based learning:

URL-Based Cards: Add any webpage—YouTube videos, articles, Netflix episodes, manga readers—as a flashcard with one hotkey (Alt+F). Lianki stores the URL, and when it's time to review, you revisit the entire experience.

Browser-First Workflow: Install the Lianki userscript (Tampermonkey/Violentmonkey) and review cards without leaving your current page. The review UI overlays directly on top of whatever you're watching.

Keyboard-Driven Speed: Rate your recall with 1-4 (Again/Hard/Good/Easy) or HJKL/ASDT. Navigate with media keys. No mouse needed, no context switching.

The Loop: Instead of drilling isolated vocabulary, you loop through entire episodes, articles, and videos. Each time you revisit content, you understand more. The FSRS algorithm ensures you're reviewing at the perfect interval—not too soon (wasting time), not too late (forgetting everything).

The Workflow: Language Reactor + Lianki

Here's how to combine these tools into a language learning superpower:

Setup (5 minutes)

Install Language Reactor Get it from the Chrome Web Store. Works on Chrome, Edge, and other Chromium browsers.
Install Lianki Userscript Visit lianki.com/lianki.user.js and install via Tampermonkey or Violentmonkey (free browser extensions for running userscripts).
Sign up for Lianki Go to lianki.com and create a free account (email, GitHub, or Google sign-in).

The Core Loop

Step 1: Find Content at Your Level

Open YouTube and search for channels in your target language
Look for speaking-oriented content: vlogs, cooking tutorials, interviews, explainer videos
Pick something that looks interesting—ideally content where you understand 70-80% already
Pro tip: YouTubers who explain things (tech reviews, how-tos, educational content) use clearer speech than entertainment

Step 2: Watch with Language Reactor

Turn on dual subtitles (target language + your native language)
Watch the video normally, using the pop-up dictionary when you encounter new words
Save words you want to remember to Language Reactor's vocabulary list
Loop difficult sentences with Language Reactor's controls until they click

Step 3: Add the Video to Lianki

After finishing the video, press Alt+F while on the YouTube page
Lianki creates a card with the video URL
Rate how well you understood: 1 (barely), 2 (struggled), 3 (good), 4 (easy)
Lianki schedules when you'll watch it again using FSRS

Step 4: Review in Spaced Intervals

Days or weeks later (depending on your rating), Lianki reminds you to rewatch the video
Open your Lianki review queue at lianki.com
Click the card → you're taken back to the YouTube video
Watch again with Language Reactor (maybe hide subtitles more this time)
Notice how much more you understand on the second viewing
Rate your recall again → Lianki adjusts the next review interval

Step 5: Export Vocabulary to Lianki (Pro Users)

If you have Language Reactor Pro:

Export your saved vocabulary list with context
Create individual Lianki cards for key vocabulary items
Add the exported sentences as URL cards (if they link to specific timestamps)

Why This Works: The Science

Spaced Repetition + Comprehensible Input = Language Mastery

This workflow leverages two of the most proven techniques in cognitive science:

Spaced Repetition: The FSRS algorithm schedules reviews at increasing intervals, exploiting the spacing effect—the finding that information is better retained when study sessions are spaced out over time rather than massed together.
Comprehensible Input (i+1): Linguist Stephen Krashen's research shows that language acquisition happens when learners are exposed to input that's slightly above their current level—comprehensible with a bit of effort. Dual subtitles give you exactly this.
Context-Rich Learning: Cognitive psychology shows that memory is context-dependent. You remember things better when they're tied to rich sensory and emotional contexts. A YouTuber explaining how to cook, a vlogger talking about their day—these provide far richer context than a flashcard with a single word.
The Testing Effect: Every time you revisit an episode and test yourself on what you remember, you're strengthening those neural pathways. Lianki's review system bakes this retrieval practice into your workflow.

Advanced Tips

Create Video Series

Instead of adding individual videos, add entire series or playlists:

Watch a 3-5 video series from the same YouTuber
Add all URLs to Lianki in one batch (Alt+Shift+V for bulk add)
When Lianki schedules them, rewatch the series to reinforce topic-specific vocabulary

Layer Multiple Tools

Use Language Reactor's PhrasePump for daily vocab drilling
Use Lianki for content looping (entire videos and channels)
Both systems reinforce each other: PhrasePump drills words, Lianki reinforces them in context

Progress from Dual to Single Subtitles

First viewing: Both subtitles on Second viewing (after a few days): Target language only, click for native translation Third viewing (after a few weeks): No subtitles, test your pure listening comprehension

Lianki's FSRS scheduling naturally spaces these viewings out at optimal intervals.

Track Your Heatmap

Lianki shows a GitHub-style activity heatmap on your homepage. Each review day becomes a green square. Use this to:

Maintain study streaks
Visualize your learning momentum
Spot patterns (do you review more on weekends?)

Add YouTube Channels

Language Reactor works beautifully on YouTube. Add entire channels as cards:

Find a YouTuber who speaks your target language clearly
Add their most recent video URL as a Lianki card
When you review, watch a new video from that channel
Over time, you'll naturally understand more of their content

Real-World Example: Learning Spanish with YouTube

Let's say you're learning Spanish:

Week 1: Find a Spanish cooking channel (say, "Cocina con Carmen"). Watch a video about making paella with Language Reactor. Add it to Lianki, rate it 3 (Good).

Week 2: Lianki reminds you. Rewatch the paella video—you understand more, the recipe steps are clearer now. Rate it 4 (Easy). Add another cooking video from the same channel, rate it 3.

Week 3: PhrasePump drills you on "sofreír" (sauté), "fuego medio" (medium heat), "añadir" (add)—all words from the cooking videos. You hear these repeatedly across multiple videos.

Week 4: Lianki shows you the first paella video again. This time, you barely need subtitles. Rate it 4. The second video comes up—easier now. You add 3 more videos from Carmen's channel in a batch.

Month 2: Your queue is a mix of cooking channels, Spanish tech reviewers explaining gadgets, travel vlogs, and language learning podcasts. You're looping through all of them at FSRS-optimized intervals. Your vocabulary is growing, your listening comprehension is skyrocketing, and you're having fun.

Month 3: You branch out—add a Spanish gaming channel, a podcast about history, a lifestyle vlogger. Each new channel introduces domain-specific vocabulary, but the core conversational patterns repeat everywhere.

Month 6: You realize you're watching Spanish YouTube without subtitles and understanding 90%+ of it. You didn't "study" in the traditional sense—you just watched content you enjoyed, looped it, and let FSRS do the work. When you finally try watching a Spanish movie, the dramatic dialogue feels surprisingly easy compared to fast-paced YouTuber speech.

Why Not Just Use Anki with Language Reactor?

You absolutely can export Language Reactor vocabulary to Anki—many learners do! But here's where Lianki offers something different:

Content-First vs. Word-First Anki is word-first: you're reviewing isolated vocabulary cards. Lianki is content-first: you're reviewing entire experiences (episodes, videos, articles). The vocabulary comes embedded in those experiences.

Frictionless Integration One hotkey (Alt+F) adds any page. No copy-pasting URLs, no manual card creation. Review overlays on the content itself—no app switching.

Lightweight & Portable No desktop app to install. Works anywhere via userscript. Syncs across devices automatically.

URL-Based Philosophy Lianki is designed for the web. If you're learning through online content (YouTube, articles, streaming platforms, manga readers), Lianki meets you where you already are.

That said, you can use both: Anki for drilling individual words exported from Language Reactor, and Lianki for looping through the source content. They complement each other beautifully.

The Bottom Line: Learn While You Watch

The future of language learning isn't textbooks or isolated flashcards—it's immersion made accessible. Language Reactor removes the friction of finding and understanding native content. Lianki ensures you don't just understand it once, but loop through it at scientifically optimized intervals until it's permanently encoded in your memory.

Together, they turn your YouTube subscriptions into personal tutors, every video into a lesson, and your entertainment time into the most productive learning hours of your day. Netflix and other platforms work too, but YouTube's speaking-oriented content—vlogs, tutorials, interviews—offers the clearest, most comprehensible input for language learners.

Getting Started Today

Install Language Reactor on Chrome
Install the Lianki userscript (Tampermonkey/Violentmonkey)
Sign up at lianki.com
Find a YouTube channel in your target language (cooking, tech, travel—whatever interests you)
Watch a video with dual subtitles
Press Alt+F to add it to Lianki
Come back when Lianki reminds you

That's it. You're now language learning the smart way—by doing what you already love, but with the science of memory on your side.

Start with YouTube for the clearest speech and most comprehensible input. Branch out to Netflix shows and movies once you've built a solid foundation.

Happy learning! 🎬🧠

Sources

Further Reading on Lianki: