The actual Jim Henson Hour versions of Food/The Three Ravens, Living With Dinosaurs, and Secrets of the Muppets that you will have seen are all unaired versions taken from master tapes. [As is Inner Tube / Pitch Tape, of course.]
However, there are also aired versions of Food, The Three Ravens, Living With Dinosaurs, and Secrets of the Muppets - different edits that aired as specials on their own. You'll find those at Henson Rarities as well.
The Henson Rarities channel is probably the first time you'll have seen the original "Jim Henson Hour" version of Secrets of the Muppets, rather than the Nickelodeon version. "Food" aired as part of The Jim Henson Show, and The Three Ravens as part of The Storyteller, of course. Living With Dinosaurs aired on its own [on Channel 4 in the UK and elsewhere] without Jim's intro.