Thanks to much to ILVtheFAB4 for this information:
I just read the news item that had the song Nick sang in the Behind the Scenes video, and I thought I’d add the song Bill played on the piano at the end of the video.
It is “You Like Me Too Much” performed by The Beatles, written by George Harrison of the Beatles. It is from the album “HELP!”
Full lyrics can be found here:
“You Like Me Too Much”