The guy singing is Bill Danoff, and he and his wife next to him Taffy Nivert co-wrote one of my fave John Denver hits entitled, WELL I GUESS HE'D RATHER BE IN COLORADO. They also wrote TAKE ME HOME COUNTRY ROADS.
Despite the perm, the tux and the 12 string gig he was a respected songsmith in his day.
lol! Bill is a friend of my brother's. He and his current wife (who is not Taffy) owned a club in D.C. called the Starland Cafe. I just looked at the website and evidently it recently closed. He's still performing though http://www.billdanoff.com/