David said he was "nervous" about performing it, and although you couldn't hear it in his voice (he sang brilliantly - read the vids comments on the YouTube page!) I bet he was because the song is very complex and has some amazing notes in it. I'm thrilled they added it to the show and I hope he sings it at other shows as well.
And I really love the small changes to the songs arrangement. Very nice job on the keyboard as well.