Knockout Study

knockOut Study — learn languages by watching what you love.

knockOut turns YouTube and Bilibili into an interactive language classroom. When subtitles are on, every word in the subtitle line becomes tappable. Hover for a quick translation. Click for the full dictionary entry — pronunciation, part of speech, example sentences, and synonyms — without ever leaving the video.

How it works
Enable subtitles in the YouTube or Bilibili player as you normally would. knockOut captures them, processes them, and overlays a tappable version on top. The original video experience stays untouched — you can still pause, seek, and use all native controls.

Features

Tap any word — instant dictionary lookup with translations, pronunciation (pinyin, romaji), part of speech, and example sentences
Hover preview — see the top 3 translations without clicking
Save words — build your personal vocabulary list as you watch
Phonetic mode — display pinyin or romaji as ruby annotations above every word
Draggable overlay — position the subtitle line anywhere inside the video; snaps to center
Keyboard shortcuts — A / S / D to jump to previous, repeat, or next subtitle line
Fullscreen & cinema support — works in all YouTube and Bilibili layout modes
Instant re-play — subtitles are cached locally so revisiting a video loads instantly
Supported platforms

YouTube (all languages with subtitle support)
Bilibili (Chinese, including AI-generated subtitles)
Supported study languages
Chinese (Mandarin), Japanese, Korean, and more — with romanization support for each.

Sign in required
knockOut requires a free account at knockoutstudy.com to look up words and save your vocabulary.

Privacy
knockOut only processes subtitle text you explicitly enable in the player. No audio, no video, no browsing history is collected. See our full privacy policy at knockoutstudy.com/privacy.