I've found Hover Scroll to be invaluable in my struggle against Repetitive Strain Injury while using Firefox.
However, it becomes a nuisance on some websites such as YouTube. I wish there was a hotkey that could temporarily disable hover scroll or, better yet, a Firefox extension that could do it on a site by site basis.
There's an option to disable Grab Scroll, etc. with a hot key and would appreciate having that option for Hover Scroll.