Rated 3 out of 5 stars
Update works just fine.
Thank you for reacting so quickly!
edit (30-September-2012): I think it’s not working again (FF v. 15.0.1; add-on v. 1.0.3, YT HTML5 is off).
Rated 5 out of 5 stars
This is actually the first addon\script\whatever that was supposed to prevent Youtube autoplay and worked for me. I'm on v.13, btw.This review is for a previous version of the add-on (0.2.91.1-signed.1-signed).