YouTube™ Enhancer Plus
YouTube Enhancer Plus is a Firefox add-on that greatly improves your YouTube experience. It allows you, among other useful things, to automatically play videos in HD or any other preferred format, disable autoplay for videos loaded in background tabs, play videos in cinema mode for a comfortable and distraction-free watching, repeat videos over and over without clicking replay, change YouTube's style using custom themes, and more...
One of the most appreciated feature is the possibility to remove ads from videos, whether automatically if you don't want to see them at all, or manually if you want to only remove ads that don't interest you, and want to permit channels you're subscribed to to earn revenues from those ads so that they continue to produce great videos.
Another feature that is really appreciated, mostly by multi-tasks users having a large screen, is the sidebar. YouTube Enhancer Plus makes use of the built-in Firefox sidebar to allow you to watch your favorite videos while doing something else, such as surfing the web, chatting, or playing online games for examples.
YouTube Enhancer Plus is part of the featured add-ons for Firefox and is used daily by more than 100,000 persons, so if it's not your case and you want to try it, click the button below to install the latest version directly from Mozilla's website, it's free!