YouTube Fullscreen Anywhere by Aendryn

A tiny Firefox extension that fills the browser window (not the monitor) with the YouTube player.

The native Fullscreen API always targets the monitor, so this fakes it: pressing Alt+W pins YouTube's player to the viewport with CSS - filling the window. Press Alt+W again or Esc to exit. Pure CSS/JS, OS-agnostic, collects no data.

Source code available at: https://github.com/aendryn/youtube-fullscreen-anywhere