VidLingo Sync for Chrome

Two things our servers can't do on their own. YouTube only shares its captions and translations with a real browser, so with this extension a YouTube video on VidLingo gets them free: the captions in its own language, the uploader's translations and YouTube's automatic translations, saved for everyone. And Instagram's, X's, Douyin's and Bilibili's players keep the video's position to themselves; the extension reads it so the words light up exactly and the play, pause and restart buttons control the video.

What it does, and what it does not

Runs only inside YouTube, Instagram, X, Douyin and Bilibili players that are embedded on a VidLingo page. It does nothing on those sites themselves.
Sends the page the video's current time, whether it is playing, and (for YouTube) the video's caption tracks. Nothing else: no account details, no browsing, no cookies.
Takes play, pause and seek requests only from VidLingo pages.
Needs no sign-in and asks for no permissions beyond those two players.

Install it

The Chrome Web Store listing is in review. Until it is published, install it from the source code:

Download the extension folder from the repository (extension/) and run npm install then npm run build inside it.
Open chrome://extensions, turn on Developer mode (top right).
Click Load unpacked and choose the folder extension/.output/chrome-mv3.
Open any YouTube, Instagram or X video on VidLingo. YouTube videos gain YouTube's captions and translations; on Instagram and X the bar under the player says “Synced by the VidLingo extension”.

Without the extension

Instagram, X, Douyin and Bilibili videos still play. Tap the video to start it; the play, pause and restart buttons keep the transcript in step, tapping a word moves the transcript there, and the −½ s and +½ s buttons nudge it. Or, when you add the video, choose a private copy: it plays here with exact highlighting, and stays private to you.