Don't really want to make this thread all about unrelated discoveries from the archives (do we need a thread for such a thing?), but that Sesame Street Fever movie sounds intriguing. The plot sounds odd - in this universe the Muppets are just television characters and a kid imagines them as real? The eventual Sesame Street movies feel more than just "Sesame Street: The Move" (after all, they don't cut the plot for random unrelated sketches), this feels like it would have been that but with a different main setting. Of course those memos came before The Muppet Movie was completed so maybe they weren't caring so much.
And it's interesting that the memo says that they had considered movie possibilities before, only for studios and producers to tell them to go nowhere near that medium. It is good that they never gave up on doing a movie, and I guess the success of the first three Muppet movies proved that Sesame Street could sustain a marketable movie (well, the success of the first two, Follow That Bird was likely in development/filming as MTM was being released). I'd like to see more memos on Sesame Street movie concepts (as well as memos about FTB and EIG).