See my newer post on this subject.
I know I’ve been through this before because I’ve setup Fedora before and it’s working. But I just installed FC12 on my desktop at home (since my Seagate drive bricked itself a few days ago and I had to reinstall anyway) and while I finally got the Adobe Flash plugin working, it didn’t have any audio, which made YouTube kind of suck. Anyway, this of course was a solved problem, I just forgot where the fix was located… but duh, it’s on the Fedora website. A simple
yum install flash-plugin nspluginwrapper.x86_64 nspluginwrapper.i686 alsa-plugins-pulseaudio.i686 libcurl.i686
and everything appears to be fine. Thank you Fedora!