Maybe it's just my definition of what clear and obvious should mean, but whilst I know what you are saying about looking at numerous fouls, surely clear and obvious should be something you can reasonably expect the referee to spot, and easily spot after a couple of replays. If you have to watch it over 10 times, start looking at 3 or 4 different incidents, spend ages trying to determine which foul occurred first by slowing it down to frame by frame, then surely it's not clear and obvious. It's not something you'd reasonably expect the referee to spot with the naked eye.