It is performed by classical pianist Lang Lang during a rehearsal at Boston's Symphony Hall on 27 February, 2013. He is a true showman. I thought it would be different to show him rehearsing rather than playing at a serious concert.
Once again, hoping this will come through OK. This is, of course, me experimenting and with my minute knowledge of computing in general I always have my fingers crossed (or would if I could cross them). (*:*)