Works as described and no real problem here except for one issue which is maybe nitpicking seeing as the code is available on Github and I could implement it myself except I can't use it outside adding it temporarily in about:debugging due to the fact that when I try to add it on the browser as a zip file with the minor edit Firefox gives me a corruption error. That's probably my own fault and I'm likely doing something wrong.

Anyway, an option to use a custom keyword would be nice. I'd opt for "yt" personally instead of having to type out the whole word. I didn't come across a way I could contact the dev so hopefully I can get some kind of response on how to do what I want leaving this review here.