Theater Mode is a addon that help you focus on the video when watching online contents. It simply darkens the whole page except the video and let you watch the video without any distraction.
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.
In order to work with this addon, simple open a website with a video content(s). Start 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 in the addon homepage (http://mybrowseraddon.com/theater-mode.html).