Would be an interesting feature to be added, saw someone posting about how they have to make a youtube channel to report hackers. In PB2.5, they could simply be prompted whenever they leave a game if they would like to save the gameplay or whatever.
Probably wouldn't be able to save as an .mp4, so the easiest way to do it is have whatever file format flash uses (I think maybe .swf) and if there is way to upload gameplay sessions, be sure to have a watermark of sorts in the files so people don't try to upload anything malicious