"Looking at the picture below and understanding that United 885 was fueled for a flight to Osaka (About 10:30 @ FL320 plus reserves) it could just have very quickly turned into a horror movie for the two (or three, or four) ladies and gentlemen at the pointy end of it had flight 214 been 200 feet to the left of the initial point of impact. It seems that this would have changed all the numbers of casualties."
From other videos and still pics I've seen, UA was still on the parallel taxiway and had not made it to the hold short line yet. They probably saw the initial impact, but doubtful much of the final slide and evacuation. Asiana would have had to have been much more than 200' left of center to cause a disaster on this one, however if UA had been there, you are spot on.