I've received several suggestions as to who the mystery man behind the door was in the Emmy video. None convince me. I don't think it was Bob Barker and that they just put him in later because the dance number was choreographed and the lighting cues and camera moves were all prearranged. They had to have had someone behind each door when it was scheduled to be opened. I also don't think it was Peter Falk and they just moved him later, into Walter Cronkite's bit. The Cronkite/Falk moment was too perfect to have been an accident. And I don't think it was Jimmie Walker about to yell "Dy-no-mite" because he did that in one of the film clips.
I accidentally posted the next-to-final draft of my long reply to Johnny Achziger — who, by the way, is definitely one of the good guys. I have now replaced it with the final draft, which is slightly longer and contains fewer typos.