I had to stop using it because in every case, no matter what settings I set, the keyboard controls stopped working after watching a video for a while. Specifically the spacebar. When I first loaded a video on youtube and started fullscreen playback the spacebar worked as normal. Press it once to pause press it again to resume. But after a fairly short time (Maybe 15 minutes) of video playback pressing the spacebar will only pause the video while you hold it down. As soon as you let off the spacebar playback resumes. If you hold it down long enough it will start switching rapidly between pause and resume, but in all cases playback resumes as soon as you let off the spacebar. So it becomes impossible to pause the video playback with the spacebar, you have to use the mouse, which is extremely irritating as I use a wireless keyboard to control playback when not sitting at my computer. Using the mouse in this situation is not acceptable. I have observed this behavior on Windows 10 Build 1809 and on Ubuntu Linux 18.10. On Firefox 64.02 and 65 beta. As soon as I remove the extension, the problem goes away. It's a shame because I really enjoyed most of the other features.