I think the speed "estimate" are a bit high too, but here and almost always with motorcycles it is more the noise that annoy me.
I very much like the south park episode on this matter.
It was a calculation rather than an estimate, so I was assuming it was approximately correct, was just thinking that he must have good brakes to have made it around the corner, as well as brakes that hadn't overheated yet!
Not going to download the video and check the calculations though...
My calculations are not very scientific I agree, although I have been around that corner at 140km/hr in a 4x4 so it's not that sharp. He may have slowed down before going round the corner as well.