This first comes from the Royal Variety Performance in performance, and it may be the only performance of Mary Martin together with her son, Larry Hagman. And it's a wonderful 14 minutes long, with five (count 'em, five) songs.
At the time, Larry Hagman was at his peak as J.R. Ewing in Dallas, so that heightens the drama of the moment, and he sings here a funny homage parody of his mother's famous, "My Favorite Things." It's not a strict parody with the same tune, but it's called, "My Favorite Sins." It's clear that he's nervous and a bit out of his element because he screws up big time, and eventually just gives up. But he does much better with a second number. What comes through it all though is that he's thrilled to be performing with his mother -- and that, too, might be the cause of some of his nervousness. After all, the sage is her element.
By the way, this isn't precisely the only time they performed together, though it is as solo performers. As they note here, he was in the chorus of that same London production of South Pacific. And it's worth mentioning that though he is uncomfortable singing, he actually was in a musical in the '60s, called (oddly enough) The Nervous Set. I even have a copy of the cast album in my offensively-large collection. So, he does have some singing ability.
But, of course, the real treat is when Mary Martin arrives on stage, and the two perform together. But it's really her doing the show-stealing performance. Fun, too, is it's a re-creation of that song we just had, "Honey Bun," and in her same Seabee costume. She is just a bundle of utter exuberance. And impressively spry. She's a joy to watch.
But what a treat to see them together. And have this footage.