How long can you actually hold your arms straight up? I stood in the projection box and tried it against a reel change — two minutes, and my shoulders began drafting a letter of complaint. Henson's lot did it for hours, crouched under the set line, and the thing that makes it possible is a monitor laid on the floor where they can see it. You don't watch your own hand. You watch the frame, the way the fourth row will see it, and you fix the frog's eyeline to that instead of to the room.
Cut to the crew, all of them turned away from the performer, looking at a screen — which is roughly my job too, since from the box I mostly watch the backs of heads. He was born in Greenville, Mississippi, in 1936, and there's a lot with a gate marked 1416, half-timbered brick behind it, and a green frog up on the tower with his hat lifted.
Paul Williams and Kenny Ascher wrote that banjo song for him, and the vocal went down in one take, loose as anything — no pushing. Listen for how far back he sits off the beat in the verses.
Steve Whitmire, who took over Kermit after Henson, shares the birthday — born 1959. Two Kermits, one date (I checked twice, because I would).