Being a recently-inducted fan of Dream Theater, I downloaded as many videos pertaining to them as I could off Kazaa. One was Erotomania Live. Excellent song. But the thing that got me was, at certain parts, where he wasnt using his left hand for anything, Mike Portnoy would twirl the drumstick in that hand, and then hit himself in the head two times before resuming drumming. He does this several times in fact. For those of you who have this video (I believe it is from Scenes from NY) you can check it out for yourself; the best example is around 1:50 into the song. His right hand is doing most of the drumming, so he twirls the left stick and then hits himself twice in the head. Or at least thats what it looks like
Can someone explain to me what exactly he is doing? 
