Back in the early 90s, I wrote the liner notes for Sony's Firesign Theatre box set, and I got to interview all four Firesign guys, which was a genuine thrill, as you can imagine. Talking about his pre-Firesign work, Austin mentioned "Duckman" in passing --
Originally monikered the Oz Firesign Theatre (by Bergman) the group later had to shorten the name when lawyers for Disney and MGM - who owned the Oz copyright - threatened legal action. Whatever they were called, however, the group and their freewheeling, sounded-stoned-but-wasn't brand of improvisational comedy were an immediate hit with the nascent underground audience. And as the Summer of Love loomed, they inevitably came to the attention of a record company, in the person of Gary Usher, trend-savvy producer for CBS and veteran of the L.A. surf music scene who had earlier done a comedy single - "Duckman, Parts I and II" - with Austin ["Because I could do this duck voice," Austin says. "It was just stupid."].
-- which is the only reason I knew of its existence.
YouTube being the equivalent of the Library at Alexandria, it did not surprise me to finally run across it a few weeks ago.
Nor did it surprise me to find myself in complete agreement with Austin's assessment.