Solid, and reliable. I have a few little nitpicks, but they're just personal preference, not really a mark against the extension - I have a keyboard-shortcut set up to open this extension, but this shortcut won't work unless the extension button is pinned to the address bar (i.e. like in the screenshot included on this Firefox Add-on page). I would love if I could remove the button from my address bar but have the keyboard shortcut still work, since the button adds to my already-cluttered list of extension buttons. I don't know if this is possible, but adding a floating volume-boost button over videos (similar to Firefox's built-in Picture-In-Picture button) would be incredible, but I can understand if you don't want to implement this. Again, very useful, best extension for this job.