The CSL's traction control system will let the car get between 15-20 degrees off center before the traction control takes over and makes sure you don't over-cook it.
From my point of view, this means that all you have to do is mash the pedel (no need to actuate it like you would in a "real" drift) and steer the car. So, though his drifts may look perfect and amazing, it's really just the car's electronics letting him work the ass-out so perfectly.
Not that it stil doesn't look sick as hell.

I just give the props to BMW and not the driver.
-Prince