Hey, I couldn't get your extension to work for my particular case. I'm trying to stop movies and videos or livestreams from freezing in the background. I noticed the videos freeze after 10 seconds if I open a different tab in fullscreen. But I did a lot of digging and I fixed it by going to about:config and changing media.suspend-bkgnd-video.delay-ms to a really high value. Might be something to look into