After installing the Adobe flash plugin within Firefox on my Fedora 9 box, I could not get the sound to work at all on sites such as YouTube.
A quick google told me that I had to install libflashsupport.
After running ‘yum install libflashsupport‘ , everything was well with the world. This library allows Pulse Audio to work with flash apparently.
If I can find the original source of this fix, I’ll be sure to update this post with an acknowledgement – They saved me a lot of time!