I had to disable it since it was causing serious issues to some websites that had nothing to do with youtube. The developer kindly replied saying the issues would be addressed, but I wonder if I can now trust it won't do the same again, with some other website/web app.
EDIT May 2022: still causing issues, and preventing checkout via PayPal to work at all. Such a pity I have to delete this extension permanently because it's a real disaster.

cannot remember playback speed of each individual sites. I want youtube video to play at 1.3 but that speed carries to ALL video on ALL sites

It is not your extension. it stopped working.
I rebooted everything reinstalled , no good. Then I tried the flash player controls and it does not work either. chrome works fine. i think it may be firefox. can you help me out on this

deixou de funcionar no firefox.... já desisntalei e reinstalei tanto o firefox quanto a extensão, mas não voltou a funcionar

Stops working after 1-2 videos. Only way to make it work again is to remove and add it again.

good