The product supplied to the network by Hanna-Barbera in those days were mostly reruns picked up from other networks (i.e. The Flintstones, Josie & The Pussycats) or made-for-TV movies that somehow failed to register with audiences (i.e. "The Beasts Are on The Streets").
And, then, there is The Hanna-Barbera Happy Hour, a Thursday night variety show hosted by a pair of puppets, Honey & Sis, where celebrities tried to put on happy faces interacting with the puppets, but it was clear viewers weren't interested. ABC owned Thursdays back then, with Welcome Back, Kotter & What's Happening! airing from 8-9 (ET).
Edit, 2/28/22: WB has filed a copyright claim, removing the video. In its place is a network print ad.
Celebrities in hot tubs? The Kroffts tried that several months later with Pink Lady & Jeff, and, yes, that, too, bombed, although Pink Lady, a Japanese pop duo of the day, were more appealing than a pair of puppets passed off as teenagers. Something tells me they wanted to sell this and the subsequent Legends of The Superheroes miniseries to ABC, and the "Alphabet Network" passed on both. Remember, NBC was desperate back then.
No rating. Never saw the show. We watched either Kotter or The Waltons or baseball.