While he was still getting the whole Muppet thing off the ground, Jim Henson also created some seriously serious, experimental films. His 1964 short, Time Piece, is eight-and-a-half minutes of surreal stop-action animation and what not--including a 60's-style stripper, heads up--that was nominated for an Oscar.
In 1969, just as Sesame Street was kicking into high gear, Henson and Jerry Juhl created The Cube, a freaky, frustrating, and existentially bleak TV play [on NBC!] about a nameless guy trapped in a white room. All sorts of visitors wander in and out, but he can't escape. It boggles my mind that it was on actual network television.
Anyway, I'd looked unsuccessfully a few times for screenings or copies of Henson's early work. It's possible but not clear whether the screening program at the Smithsonian's just-opened, Jim Henson Legacy exhibition will include some of it. But I just found both Time Piece and The Cube--in color, no less--on Google Video. Several versions of Time Piece are listed as having been removed, so the time to view them may be limited.
Watch Jim Henson's Time Piece: 8:49 [broadcaster.com via google video]
Watch Henson & Juhl's The Cube [google video]
Jim Henson Legacy runs at the Smithsonian from July 12 to Oct. 13 [jimhensonlegacy.org via dt reader sara]