Maybe not completely lost, just really hard to find, it might be on one of the DVD special features, but it doesn't seem like it is. The pre-pilot test animations for the Human Flesh episode of Bob's Burgers that used the original cannibal concept, the artstyle was like pic related and used a weird mocap-like animation.
I remember watching it on YouTube a few years ago, it's basically like the scene from the actual episode with Bob and Linda at the meat grinder (
https://youtu.be/6gsKIFtULkA), except instead of grinding meat chunks its human body parts. The scene basically played out the same way it did in the episode: Bob forgets about the anniversary and Linda thinks he's planning a surprise party, except towards the end there's an extra scene with Linda finding a nice ring and pair of shoes in the severed body parts, thinking that they're anniversary gifts from Bob.
I really wish I could see it again, it was pretty funny, having the show's usual dry humor, yet absolutely bizarre at the same time over how non-chalant they were over the bodyparts
