YouTube Theatre Mode от Adeithe

Improve the default YouTube Theatre Mode with a layout that makes use of the full browser window.

When using theatre mode with this extension enabled, the video player will take up the full width and height of the browser. If you're watching a livestream, the chatroom will also be displayed unless closed.

The layout is designed to be as similar to the theatre mode on Twitch as possible.

Having issues?
If you have this extension installed, have refreshed any open YouTube tabs after install, and the extension does not seem to be working - Go to the Firefox Add-ons Manager > YouTube Theatre Mode > Permissions and data > Enable access to youtube.com