Wow he went down hard! It's kind of scary that someone could get so ****** off about this kind of this that they would literally try to chase you down...what the heck did he think he was going to do if he caught the guy on the bike?
Still, as wrong as driver was, the cyclist had to have known that he was provoking trouble with the way he approached the situation. He could have told the driver he was too close and left it at that instead of letting it turn into an argument, because honestly there's no way to win in situations like this. You never know what kind of psycho you're dealing with either, it's just not safe.