I don't want to appear disloyal - I've used VDH for years with Firefox (also a constant companion since Netscape Navigator days) and encouraged many family members and friends to install it in its full fat converter version - but some battles are maybe best to walk away from?
It's good to know that the development team has just doubled, and the fact that the new recruit used to work for Mozilla is particularly encouraging. Indeed I would suggest that Firefox has been behind the demise of a number of add-ons, as they suddenly became incompatible. Some recovered, some didn't.
But my solution for YT videos is simply to use *eplay *edia *atcher from *pplian which often gets me quickly out of downloading problems, and also extracts mp3 files from music videos with a right-click. And no headaches.
If I hear that the YT issue has been solved, I'll be glad to return to VDH for that purpose, not least because it's good to have all my downloads in one dwhelper folder, and VDH does just about everything else so well. And the advice in this group is excellent 👍
Just a thought.
Mike