it used to work when i first got it, long time back and i REALLY loved it... but haven't needed to use it for a while and now have noticed that for some reason, now it really only works for me like 2% of the time, it however does constantly completely mute any tab that i try to use it on and the only thing that can be does is to reload the tab, which of course makes the sound volume reset back to normal. if you ONLY want to watch youtube in one tab, this add-on would be fine, that's about the only site i can get it to work with any more... i would also suggest, next time you update this extension, add some settings to it where i can change the automatic default and that it would apply to ALL tabs, or at least have that option... i wouldn't have any issues with the extension at all if i could just go into settings, set it to default 400%, across all tabs, wouldnt be any need for tabs reloading or adjusting it for each individual tab or video, wouldnt have to wait for the video to already start playinig before ii can adjust the volume, two little suggestions would fiix the whole extension, for me anyways. i'm so disappointed but until it get's fixed, i'm going to try some of the others that reviewers have suggested for now since this one doesnt work :(