Watch some 'formula drift'. They're powerful enough that they don't need to use the front brakes to spin the tires, even at speed. It's possible the same thing applies to the bike, that it's just overpowering the rear wheel and not using the brake, but since he doesn't accelerate out of sight, he probably is braking.

It is about speed. They aim to be the fastest and the most sideways, and there are also points awarded for style.

The formula drift scoring is described here, and seems fairly similar to the other competitions I've seen televised:

http://www.formulad.com/info/judging-info.php

That was one hell of a lot of road closures.
Formula drift sure has upped their game as far as locations go.

Woah!!! For anyone that hasn't seen it, I highly recommend searching for the Mustang Drift videos. They're somewhere on Ford's website but it's a very impressive series of videos for the new Mustang. They get one of the top US Formula Drift drivers to go to Japan with a 500hp mustang. It's really cool seeing an American muscle car driving around Japanese streets, using their automated car parks and drifting on some of the most notable tracks in all of Japan.