This is from Epsisode 55, "Telethon", which originally aired on December 19, 1997. The animated gif above has every frame of Coco's entire appearance on the show. He had just enough time to shout "Moltar!", before Moltar pulled his lever and switched to a different feed.
Shamefully, the online transcripts for this episode omit any mention of Coco's sub-second appearance. I'll put up a corrected version here soon, along with other material documenting the connections between Space Ghost and the primary subjects of ASR3K: Man or Astro-man? and Mystery Science Theater 3000.
Go to the ASR3K Records Virtual 7" Singles page to hear the MOA? music for SGC2C .