Did you notice how much he REALLY didn't want to do that? I felt kind of bad for him, heh. I think he has a cold and looks exhausted.
It's the same with his impersonations. For the first few times it was all fun for him and for fans. Now he's been asked over and over again to dance and it's kind of losing its novelty. At least this time he sort of promised he might do it at the start of the week and the ball girls made it less awkward for him.