It is pretty bumpy in certain spots. It's hard to tell from the video, but I think that's a spot where you can easily spin up the rear if you apply too much throttle while the rear is unsettled. I can even spin up my rear on my 60 HP FZR400 so it would be really easy on a GSXR. That's my theory.
edit: I think that might be a little bit before the bumpy spot I'm talking about, but plenty of riders have high-sided there in races and practice. Throttle control people... don't jerk open the throttle!
Here is a vid from a pretty fun race I had at Willow Springs a few months ago.
WSMC 550 SBK - November 2006
At 3:30 I pass three pretty good racers (2 FZR400's and an SV650) and then you can see their lines. The lines that we take in T6 through T9 are different than bigger bikes because of our low HP. There is also some pretty good passing towards the end of the video that shows you the multitude of lines that you can make work.