Three guys more or less associated with the Seinfeld Show are gathered on this clip from the Merv Griffin Show: Merv Griffin, Buddy Rich and the Velvet Fog himself, Mel Tormé. Buddy Rich's drum set falls apart at the end! And Mel Tormé actually does some nice singing. Mel appears in the episode The Jimmy, where he sings "When You're Smiling".
See also a clip from the episode where Kramer installs the set from the Merv Griffin Show in his apartement