These are some of the greatest boxers in history, for many reasons. Speed alone does not make one a great fighter. There are many gym fighters who are scary when hitting the pads, speed bag, or even the heavy bag. What made these fighters fast was not their hands - it was their body control and eerie sense of distance and timing; the ability to see live, in time and space, what an opponent was doing, how he would react to a given punch and where he would be as a result. It's the same uncanny vision that enables a baseball player to hit a 95-plus mph fastball or a Michael Jordan to make opposing players look lie they are standing still as he penetrates to the hoop.
Where does that come from? I don't know. I do know that I've experienced that feeling and skill many times, to a much lesser degree than you see on those videos, but don't know from where it comes. I do know that I just get into a zone and am laughing inside, not mocking my opponent, but laughing with joy at the experience of moving, slipping, sliding, and countering, or blowing through his defense, then clearing before he fires back.
Some of the saddest times in sports, for me, are when these phenoms are on the decline; watching them display a loss of the vision and timing that made them untouchable, and descend to the ordinary.
In MMA, the only thing that I've seen come close to this mastery is GSP or Anderson Silva. How about you?
Go over to watch the videos, and enjoy.