I'd be more comfortable with the ID if we weren't basing it on the circumstantial evidence that Nick and Harpo had a business relationship and Joe didn't. Remember, Joe knew everybody. Especially if they were high=stakes poker players, as Chico and i believe Zeppo were. Harpo testified at Joe's tax evasion trial in 1941, here's a newspaper article about it:
http://trove.nla.gov.au/ndp/del/article/8150364" target="_blank
Here's a picture of him with the Marx Brothers--they were mutual friends of Irving Berlin:
http://www.glowimages.com/imagedetails/ ... sy%20.html" target="_blank
As for other film of Joe, isn't he one of Valentino's pallbearers? I would think there would be some footage of him at one of the early Academy Awards ceremonies, though i don't remember seeing any so far. There are quite a few still photos of Joe at various Hollywood functions--i was amused at the Moguls series where he turned up in photo after photo but wasn't mentioned until the third or fourth episode.
I'm not arguing for Joe, though, from the side this guy really looks like Joe but from the front, not so much, though he is looking down at the microphone and i dont' think i've ever seen Joe from that angle. I've seen comparatively few pictures of Nick.
greta