Firefox 11.0 stopped playing Vimeo and YouTube videos

[OzzieA]

I'm a long time Firefox user. I've chosen it over Opera, Chrome, and
IE. But as of late I've been using Chrome. For reasons beyond my
understanding FF has stopped playing videos, the videos load but don't
play. When I switch over to chrome - same site, same video - no
problems.

Also FF has gotten slow. One more comment - why no FF for iPad?

Thank you all in advance.