I've noticed that The Jim Henson Company has released the Dog City special on DVD under the title "Dog City: The Movie", despite the fact that the series hasn't been on DVD (except for those Amazon burn-on-demand discs), hasn't been rerun in years, and I'm sure many aren't aware of the series (there's also the fact that the special is a special and not a movie). The DVD release of the special really should have had a bonus episode or two so people would have an idea of what the series is.
I've also noticed that The World of Jim Henson lacks certain clips that would be expected. Back when I first heard of the documentary I was expecting it to have Mahna Mahna and Rubber Duckie, but neither clips appears, not even briefly and without their audio in clip montages. And now as I'm older there are more clips that I'm surprised aren't included, like Kermit and Joey singing the alphabet and the Turn the World Around number (in fact, a long time ago on Toughpigs, I saw something that mentioned this documentary, and Danny said he couldn't remember what clips were included, guessing those two clips because they are always in retrospectives... I wonder if that was a joke or if he guessed wrong). Heck, the montage of clips from commercials doesn't include any Wilkins Coffee commercials. It's also interesting how that documentary includes interviews with Harry Belafonte, yet the documentary does not include any clips from his appearances on The Muppet Show or Sesame Street.