Twitch VOD Bookmarks by araise

Twitch VOD Bookmarks lets you mark important moments while watching a
stream live, then jump straight to them later when the VOD goes up.

• Press Alt+B (or click the panel button) on any Twitch channel or VOD
  to save a bookmark with an optional note.
• Live bookmarks are captured as stream uptime, so they line up with
  the VOD's own timeline — no manual timestamp math needed.
• When you open the matching VOD, the extension detects your live notes
  and offers one click to convert them into clickable VOD timestamps.
• On VOD pages, bookmarks also show up as markers on the seek bar.
• Everything is stored locally in your browser. The only outbound request
  is a read-only, public lookup of a broadcast's start time — no personal
  data is collected or transmitted.

Great for streamers reviewing their own broadcasts, mods keeping notes
during a show, or viewers who want to relive the best moments without
scrubbing through hours of VOD.