Only problem is it was built with the Ubuntu 8.04 beta, and I had the update manager set to include "pre-release" and "unsupported" updates. Back in mid-May, mPlayer (Gnome mPlayer, acutally, my preferred video playback tool) stopped playing (some?) AVI files.
I was able to ignore it for a while. The stuff I play back on the TV most often is h.264/mp3/matroska encoded video, and that was playing back fine. It was just when the "HQ" editions of Doctor Who were delayed that needing to play back AVI became an issue.
Of course that happened on Sunday. I had to boot into Windows to play back the files (which reminds me, I should boot the machine into Windows and make sure all the patches are relatively up-to-date).
Debugging the interaction of Linux video players and codecs isn't really my specialty. Last night I decided to go the brute-force route. Rather than just reinstalling the whole system, though, I scraped out all the video playback software installed on the machine (including pre-installed stuff I never use) and just reinstalled the packages I needed (Gnome mPlayer and codecs, ffmpeg).
It worked. All of my test videos work. There's even a little less crud on the machine.