I actually just got started on Ubuntu... I've only had a little bit of experience with Linux before, but I know a little bit about getting around and such.
I know that last night sound was working for flash videos, such as YouTube. But now they're not... I'm using Firefox 3.0 (I believe) on the newest version of Ubuntu. Updated last night.
If you need any other information, go ahead and ask. (:
P.S. - I just checked, and it won't work for Homestarrunner.com, so... It's just flash in general.
I updated to the newest version of Flash Player and cleared my cache, but still no help :[