Guides
Chrome video companion
Read, seek, and translate transcripts, then import a video or its current frame.
The Mosael Chrome extension uses the browser's native Side Panel and never covers the page with a floating window. It currently supports YouTube and Bilibili video pages and follows the active tab as you switch between videos.
Install#
Download and unzip mosael-browser-extension.zip from a GitHub Release:
- Open
chrome://extensions. - Enable Developer mode.
- Choose Load unpacked and select the extracted directory.
- Pin the Mosael video companion to the toolbar.
Developers can run pnpm build:extension and load browser-extension/dist/ instead.
Transcripts and seeking#
Open a video and click the extension icon. The panel reads captions supplied by the site and turns them into a timed transcript:
- Click a row to seek to that timestamp.
- Playback highlights the current cue and keeps it in view.
- Search matches both source text and translations.
- Moving to another video tab refreshes the panel for that page.
- The UI follows Chrome by default, or can be pinned to Simplified Chinese or English in connection settings.
Selecting a target language keeps the source line and adds a second line. The extension prefers a site-provided caption or YouTube translation track and only uses Mosael translation when no matching track exists. If a video has no captions, Generate transcript with Mosael runs URL import, speech recognition, and timed-result loading as one flow.
Translation, import, and frame capture#
The first use of these three actions asks you to connect Mosael from panel settings. Enter the
local backend address (http://127.0.0.1:8800 by default), sign in with an Mosael account, and
choose a workspace and optional project.
- Bilingual subtitles keep the source and prefer site captions; Mosael batches long fallback translations without changing cue order.
- Automatic transcription downloads an uncaptioned video, runs the selected ASR engine, and loads the timed transcript back into the panel.
- Import video submits the current page URL as a background media-library download.
- Capture current frame crops the currently visible player into a PNG and uses the normal asset upload endpoint.
The password is used only to mint a session and is never stored. The extension does not request cookie access or export Chrome login state. Download members-only, private, or region-locked content from Mosael with the matching Browser Pool profile.
Why the permissions are needed#
| Permission | Purpose |
|---|---|
| Side Panel | Open Chrome's native right-hand panel |
| Tabs / Active Tab | Follow video pages, seek, and capture the visible player |
| Storage | Keep the Mosael session and destination workspace |
| YouTube / Bilibili | Read current-page player and caption data |
| localhost / 127.0.0.1 | Call the local Mosael API |
Chrome 116+ is required. At least part of the player must be visible for frame capture.