I've been using this add-on for a few years, and it is fantastic. The user interface is the best I've encountered so far because it is simple, versatile, and fast. It executes what it does flawlessly, but I give it four stars because it is missing a couple of QOL features that could. I think it should have an advanced setting page where you can set defaults on a per-domain basis, so, for example, every video on [domein.tld] starts at 1.6x speed, and the ability to make it so you can choose to keep the speed consistent within the same tab after a reload.

Must be shortcut key.