For the longest time, I thought this extension was just for a bunch of unnecessary mouse gestures and whatnot, but it turns out it offers more than that. It's the only extension in the Firefox Recommended Extension program (besides Ublock Origin) to offer a means to prevent the comment section and recommended videos from loading, it can load videos in h264 instead of the default, it has it's own ad-blocker and ad-whitelist (so you can support the channels you want to), and it offers a means to lock video playback in a specific resolution (360p is great for lower end machines).

Are there a lot of features I don't really care about? Sure, but I would still say this is a must-use extension for Youtube. I've tried the rest, and this is easily the best.