Ortiz had committed a pretty obvious headbutt earlier on, so I'm sure these guys weren't putting each other on their Christmas card lists before the KO happened.
Mayweather's sportsmanship is the real loser here. The guy's supposed to be the world's best, but this doesn't portray him in a good manner.
And, WTF is with the ref having his back turned to the action?!? That guy needs to get a new job. I thought that only happened as a plot device in professional wrestling.
Overall, it's all legal. But another good example of why boxing is losing ground to mixed martial arts.