It comes down to the same problem with Muppet Babies. Will copyright be a problem? Most episodes were full of movie and TV clips from a wide range of production companies.
I've been doing some thinking and researching. I feel that they could at least have Best Ofs or single episodes or something.l Why? because not every episode features copywrited materials interspearced into the show. Especially in the later episodes, movie clips were nothing more than stock footage. maybe an occasional bit, like the Nintendo video game clips in "It's only Pretendo." As Gonzo said in one episode, refering to the fact they couldn't use clips from batman, "Are you nutz? Warner Brothers wanted a million dollars for a three second clip."
And I've said what i've said before...
Jeffery Scott would hit the roof if clips of the Three Stooges wouldn't be used (he's Moe's Grandson, after all), George Lucas has an excellent relationship with Henson and Disney (hense the theme park Star Wars Muppets), so he'd pull for Star Wars and Indiana Jones clips. Only thing that would be a problem is various other clips used from Columbia, in which Henson had a partnership with them in the 80's. Maybe some sitcom clips down the line would be hard to clear, but I feel they could do it.
They problably just don't want to. look how long it took them to release their own Disney Afternoon sets. And most of them are unfinished.