After watching the video, this is one of those 'attacks' that I hate. It's not an attack by any means. They are being baited in by humans. Sharks are going after the free food and missed. Sharks miss the food far more than they get it in situations like this where people are tugging it away at the last second to save the bait, so the sharks learn, and react by trying to guess where it will be pulled.
Small shark bit big shark, big shark ends up with little shark it his mouth as he turns back down. Not bad at all. I've seen worse from breeding.