Theater Mode is an addon that helps you focus on the video when watching online content. It simply darkens the whole page except the video element and let you watch the video without any distractions.
Please note that theater mode is not designed for normal browsing. Only enable it if you want to watch a video, otherwise, the whole page will be dark. There is also a whitelist feature in case you want to permanently exclude a website from theater mode.
To work with this addon, simply open a website with video content(s). Start (play) the video and then click on the theater mode button in the toolbar. The whole page will be converted to dark but the video remains visible. If you have a feature request or found a bug to report, please fill the bug report form on the addon homepage (https://mybrowseraddon.com/theater-mode.html).