since the addon has been updated, i updated my feedback and rating too.

my initial feedback:
i had been looking for such an extension for a very long time, and i am really grateful for it. sadly there's a little issue that stops me from giving a better rating for now.
when a new video is loaded, the sound will be played at a much lower volume than it should, until i do any change to the volume slider, only then the proper logarithmic scaling kicks in. this is especially problematic when reading a playlist in the background, since i'll have to go back to the youtube tab, interact with the volume slider, the go back to what i was doing.
one other thing that would be more a quality of life than necessity. with this proper volume scaling, i find myself never using the bottom of the slider, and often setting videos to 100% when they are a bit quiet. so, maybe slightly increasing the overall loudness would make the experience better.

For some reason this allows the volume level to be 0% yet still makes audio, then is muted if the page refreshes

The only extension that actually fixes the scaling with youtube volume. I watch via an HD tv that works as a monitor, NOT some smartphone or tablet, and the default, desktop version of youtube, the volume scaling of youtube is atrocious. I think I had installed about 4-5 other extensions, none worked. This does. There we go.

A must have extension if you are on youtube a lot.