I think I know what you mean. I saw another video of him doing pretty much the same character phrases and he said, "God I do the same thing every time. I have no imagination." He probably gets tired of doing impressions for people after a while, and I suppose he doesn't write his own parts does he?
It was strange when, my sister pointed out to me that on iCarly (I don't expect you guys to know this show) they had Greg Patillo, the beatboxing flute guy. It was funny because he is my old german teacher's brother.