Addon is not bad. Just a couple of things I'd like to see changed.
1) On a mac when you two finger scroll (which is the equivalent of mouse wheel scroll) to adjust the volume when using the "natural" scroll direction, scrolling down increases volume while scrolling up decreases volume. Just have a setting that reverses the scrolling direction, maybe have it say something like "use natural scroll direction" under the setting for adjusting volume of youtube videos with scroll wheel.
2) Really all I wanted was an addon that auto-pauses videos when I go to another tab while the video is playing. Firefox already auto-pauses youtube videos that are loaded in a background tab. That's not a big deal. The big deal is auto-pausing a video that is already playing in an active tab when you go to another tab. Is it even possible to do? Thanks.