Flashbug

After being away from my computer for a week, I got back to my desktop to discover that YouTube videos wouldn't play anymore (in Firefox). The videos would load, but quit playing after 2 seconds. Trying to coax them along would only result in another 2 seconds of play then it stops. No audio either.

A little Googling produced suggestions of un-installing and re-installing Flash plugin for the browser, but that didn't work. What finally did work is this: In Windows \ System32 \ Macromed \ Flash is a file called Flashutil9f.exe, which when run fixed my situation (after a reboot). So if you get the same symptoms as I did and re-installing doesn't work, give that a try.