This is the entire show, so if you just want to see the good fellow, jump to the 17:10 mark.
You might want to watch more than just the Mystery Guest here. That's because the first guest is a woman named Carolyn Cunningham. Although she's not the Mystery Guest, she almost could be. She's not famous enough, but her work is. (Actually, she's famous enough that one of the panelists thinks he knows who she is and disqualifies himself. And he's right.)
Carolyn Cunningham turns out to be her married name. She worked under her maiden name, Carolyn Leigh. That still probably doesn't mean anything to most people, though to some they've just sat up and said, "Yipes!" Carolyn Leigh is one of the great lyricists in Broadway history -- and probably the second greatest female lyricist after Dorothy Fields (at least up to that time), but arguably still), in such a male dominated field. She's also one of the least-known of the great lyricists.
Among her many works, she wrote many of the songs to Peter Pan (like, "I Won't Grow Up" and "I Gotta Crow"), the score to Little Me (for which I just played two songs on Valentine's Day, including "Real Live Girl"), Lucille Ball's Broadway debut in Wildcat (with the still-popular, "Hey, Look Me Over), and "How Now, Dow Jones" that had the breakout song, "Step to the Rear," which I've posted here. She also wrote quite a few hugely popular standalone pop songs -- like, "Young at Heart," "The Best is Yet to Come," and "Witchcraft." And her song "Pass Me By" from the Cary Grant-Leslie Caron movie Father Goose, written with composer Cy Coleman (her most-frequent collaborator) was a hit for Peggy Lee.
Unfortunately, one of the reasons she's not as well-known as she should be is that she passed away at the age of only 57. But that only makes her credentials all the more impressive.
So, here then is both Edward G. Robinson and Carolyn Leigh Cunningham..