Here’s the original Muppet performance (in best quality) of “Mah-Na, Mah-Na” (or “Mah Nà Mah Nà”, composed by Piero Umiliani, the song first written for use in the Italian film “Sweden – Heaven and Hell”).
This performance first aired on Episode #14 of Sesame Street, which premiered on Thursday, November 29th 1969. (three days later, on Sunday, November 30th 1969, a modified version of the sketch appeared on The Ed Sullivan Show)
This was before the same musical piece (in a different arrangement) would be featured by Benny Hill in various sketches (as beginning in 1971). (the Mah-Na, Mah-Na sketch would later also be remade most famously on The Muppet Show, in a 1977 edition on which Juliet Prowse was guest. It’s this version that people are likely most familiar with)
It starts with two girl Muppets (voiced by Loretta Long and Frank Oz) saying they could sing a song if only one other joined them. At this point, the “Mah-Na, Mah-Na” Muppet (later christened “Bip Bippadotta” for distinction), voiced by Jim Henson, comes up to them, only intoning said phrase, at which the number begins and at two points he does some scat singing. In the end, the girls leave, and he goes gradually off away from the camera.