I'm a cheap bitch, so I'd probably only offer downloadable files in a smaller format, 100K or 56K WMV or MOV files, to discourage the grab & run types. Gotta have a good server for streaming though...
I like QuickTime for the quality and the fact that it works on Mac or PC, so if I could only pick one format, that'd be it (MPEGs aside, of course).
Then again my comments come from the perspective of serving video clips on a site where they're FREE, definitely not porn (though the Femme Fatale clips I encoded today were rather hot LOL), and generally only a few minutes long at most. So what the hell do I know?
