I can't quite place who is doing Sweetums. It sounds a bit like Steve Whitmire,but it can't be him because he's playing Kermit. It also sounds like it could be David Rudman. Maybe it's Eric.
EDIT: Never mind, that's definitely David.
Good guess! It's actually Victor Yerrid.
As for using a Frackle, hey, at least it gives Bruce Lanoil something to do other than assist the others!
Frank and Jerry's characters were kind of in limbo, with both more or less retiring from the Muppets around this point. Granted, Jerry still provided his vocals for some projects, mainly Sesame ones. Eric was evidently still in training. Don't know where Dave was.
The then-host, Louie Anderson, had previously been a guest star on the Jim Henson Hour.
Before anyone gives Louie a hard time for not letting the Muppet performers ad-lib much, keep in mind that he wasn't in charge here - the producers/directors/editors were. Ultimately, they were the ones who said "we need to get through the entire game in half an hour."
While I'm not necessarily a Louie Anderson fan, I never thought it was fair that the fans gave him a bum rap just because there wasn't enough Muppety madness going on.
Tiny rant over, back to our regular programming.
