Dual Subtitle for YouTube

Dual Subtitle for YouTube shows the original captions and a translation at the same time, right on the video. Understand foreign-language videos without losing the original — ideal for language learners. ■ Features - Dual subtitles: original line + translated line, shown together - Automatic language detection: picks the video's own spoken-language track, including Shorts and auto-generated captions - Translate into Korean, English, Japanese, Chinese, Spanish, French or German — set on first install from your browser language - Interface in English or Korean (follows your browser language on install; switch anytime in Options) - Single-subtitle modes (translation only / original only) with a rolling window of the previous 1–3 lines for context - Karaoke-style word reveal: words light up as they are spoken (most accurate on auto-generated captions) - Drag the subtitles anywhere on the player; normal videos and Shorts remember separate positions - Four translation engines • Google (free): cloud translation, no setup • Chrome built-in: on-device model — offline, no rate limits, captions never leave your device (Chrome 138+) • Gemini (your own key): natural AI translation with a free Google AI Studio key • OpenAI-compatible gateway (your own key): for school/organization-issued gateway keys on supported domains - Full styling: font size, color, weight, line height, background opacity, Shorts size scale - Translation cache: rewatching a video shows subtitles instantly (auto-pruned at 30 days / 200 videos) - Keyboard toggle for dual subtitles (default G, rebindable). YouTube's own C key keeps controlling native captions — the two are independent ■ AI explanations (bring your own Gemini or gateway key) - 💡 Explain: select any words in the subtitles for example sentences, meaning, origin and nuance — answered in your translation language - ❓ Ask: type your own question about the selected phrase; follow-up questions keep the conversation - Alt+Q, right-click on selected text ("Explain with AI"), or the popup's ask box: open the Ask panel on any website, not only YouTube - 🖍️ Highlight parts of an answer, 📋 copy it as Markdown, or 📝 save it to your own Notion database ■ Privacy - No ads, no analytics, no trackers, no account - Settings sync through your Chrome profile; API keys stay on this device only - Caption text is sent only to the translation/AI service you choose (nothing is sent with Chrome built-in) - Full policy: see the Privacy Policy link ■ Works on - Regular YouTube videos and YouTube Shorts - Both manual and auto-generated (ASR) captions ■ Requirements - Chrome 138+ for the Chrome built-in translator; any recent Chrome (Manifest V3) otherwise