Jon Udell sounds like he'd like to offer multiple enclosures (given various format needs), but - there's a problem. The *cough* RSS Spec *cough*:

So, to Greg's question, which of these formats should be in the enclosure? Flash, QuickTime, or WinMedia? (Additional wrinkle: the Flash FLV format requires delivery of a Flash-based player, as well.) If I enclose all three, that starts to get hefty. And last I heard, sticking multiple enclosures into an RSS 2.0 item is a nonstarter

Of course, Winer could have written that into the spec. Heck, he could stop being a pain in the neck, and let someone else add it to the spec. Then again, monkeys might fly out of my butt, too.