Great, except on Firefox 80 on Catalina it does not allow full screen on youtube. Perhaps youtube have recently changed something and it broke this? Clicking the fullscreen icon in the bottom corner of a video maximises the window size, but not the display size of the video, which stays the same size as previously. I will come back and change 3 stars to 5 if you can fix this, the addon is excellent otherwise (and I would have sent this as a private message rather than a review, to give you a chance to fix it, but I can't find contact info)

Edited to add: I am using this with a current version of uBlock Origin. Is it also possible to suppress the overlays that sometimes come up when you pause a video?