What we have here is a clip from The Tonight Show for January 23, 1974. Johnny Carson's guests that night included Jack Benny, Mel Blanc, Maria Muldaur, Dr. Irwin Maxwell Stillman and Jim Henson…and this is Henson's spot with Kermit the Frog. You can see a bit of Benny at the end.
It's really world-class puppeteering. Henson was not a ventriloquist but he manipulated Kermit so well and gave him so much personality that you never really notice that Jim's lips are moving. (Although I always suspected that he grew the beard and mustache, which he did not have when he first began appearing on television, because they helped hide his mouth.) It's also quite charming that Kermit forgets the lyrics to his signature song…
