I've got Time Warner digital cable, and there's this iControl music channel -- you can watch stuff on demand, mostly short clips, but there's a concert section, and it has a live Mars Volta concert that's almost an hour and a half long. And it's pretty cool. The audio leaves a lot to be desired, but it's a nice show. The drummer is relentless...crazy stuff.
(just in case you have the channel but didn't know it, or never bothered looking, like me)
