was it only the APU deffered or was there more? The door to the airplane seemed open in the video, they were talking to some ground crew, seemed to be lightning outside, and you could see other RJ's in the background, which looked an awful lot like they were @ the gate already, and weren't being allowed off the plane because of lightning.

But as said earlier, once an engine is started, airconditioning can be run off of it as opposed to the APU, if the plane didn't have an APU they should have/could have started an engine, if the plane wasn't at the gate, and there was no apu, then an engine would have already been running, cause these things aren't like cessnas....the engines don't start off the batteries.