Hi,
This addon is working perfectly for me and has been so for quite many years now. I would like to thank and reach out to the developer and recognize his/her efforts to get this addon available to the public and on top of that free. I only use the free option and 720p is quite enough for me.
I can understand users frustration when suddenly it stops working because of youtube changes. I share the same frustration, it's a measure of how nice and useful this addon is. But the best thing to di is to only let the developer know about the problem and let him/her decide if and how they can help again solve the issue. It's not for us to complain without any restraint oblivious of how much and how long the addon has been useful to us.
I read the feeling of discouragement and how disheartening some comments by angry users could be for the developer as well as his/her disappointment at the fact that happy users didn't let hear from them. So here I am. I am happy this addon exists at all and how grateful I am for the developer's efforts.

A few days ago the addon stopped again to work, again because of Youtube...and tonight I juste tried to download. And AGAIN it's working, the developer did it.

In a word, thanks. Please carry on.

Best regards,
Nico