It was working perfectly and I was loving it, but after the last update of Firefox one annoying bug came up. I'm on my laptop and if I switch to fullscreen on YouTube and then my screen goes off due to inactivity after the video ended, the expected behavior is if I move the mouse screen should activate. Instead, screen powers up but stays all black (nothing come up to the screen) until I press the Esc key to switch off from full screen.

EDIT: Hey, removing and reinstalling the add-on seems to fixed the issue. How about that! I've updated my rating form 3* to 5*.