Works. However it keeps forgetting your setting (resets after changing video or tab) which makes it mostly useless!

volume in youtube resets to 100% and every new reel i click resets to 100% and have to adjust it everytime

Other people seem to have luck with using it, which is great, but it doesn't work on the specific site I tried it on (musictheory.net).

The best ever, no unnecessary features

100%? I have this on Youtube... No need to have an extension... Added and removed...

Thank you very much for this extension. Finally, I can control the volume on YouTube aggain. I must have done something wrong in Firefox because I can no longer control the volume on YouTube for example. The volume slider no longer moves. So I finally have full control again. I find the blue volume bar in combination with the round gray volume control to be a particular color highlight.Thank you very much. Well done. Now, after 8 months of use on YouTube, the VolumeControl extension works just as reliably and well as it did on the first day. I still can't move the volume slider on YouTube, but that doesn't matter because I have this extension. Despite the big changes on YouTube, this extension is still working.