I was bored one day and started playing around with flash and video.
http://loadedgirls.com/flash/
The file sizes end up bigger.
Also, I would imagine syncing audio up with the picture would be problematic, since as the other guy mentioned, you end up with a series of sequential bitmaps. You'd have to import the audio as a separate file.
But I never messed with the audio so I don't know for sure.