This addon claims there are filter rules. There are no filter rules that I could see. Searching the menu for "filter" reveals nothing. At best, you can "block" channels and videos, a feature youtube already has.

Also, installing this caused all of my firefox tabs on youtube to stop responding, forcing me to close and reopen each.

It's weird to me how strongly they are marketing this addon, too, and the uninstall page vaguely tries to guilt trip you for removing the plugin. I realize this is recommended by mozilla, but it's tripping a lot of sus metrics for me, and I can't recommend it.

Edit: Further review of the developer's responses on low scoring reviews make me even more certain this isn't a good idea. 1) The developers respond to claims the plugin slows users' browser down with "nuh uh no it doesn't" and "yeah well why don't you measure the milliseconds with dev tools?", and 2) The devs claim that voting less than 5 stars is "voting against the project". Why does that matter? Why does your score on your open source, free project matter? It's almost like you're pushing for popularity on your plugin for some other reason. It's incredibly suspicious, and that type of language is couched in incredibly manipulative undertones. *Don't install this.* This thing is full of red flags.