A huge number of MLP PMVs (Pony Music Videos) would fall under this MAP category, but they just call them Collabs (one of the biggest groups is just called "The Collaboratory". The format is more or less the same as for music videos in other fandoms - each artist is given a chunk of time of the song to make content for. Other collaborations common in the brony comunity are between a musician and one or more animators.
Some good MLP collabs:https://www.youtube.com/watch?v=Z2F6OKQu4JIhttps://www.youtube.com/watch?v=4pjbqwOW5A0https://www.youtube.com/watch?v=frkfY-V4vHkhttps://www.youtube.com/watch?v=RyHGvyvRkjchttps://www.youtube.com/watch?v=FckdpzZLhs4https://www.youtube.com/watch?v=1oQ4g-_VC2w
There is also a large sub-community centered around Source Filmmaker, a program that lets you use the Source videogame engine for making videos. These normally aren't collabs in the normal sense of dividing it up in time, but rather there is a group of people who make rigged models for SFM, and other people who use those for music videos and other content. Examples:https://www.youtube.com/watch?v=dMh7yktC2u0https://www.youtube.com/watch?v=9XOr9Wecesk
(a little racy, but more or less the MLP equivalent of belly dancing. Also, the Russian MLP community is a bit weird sometimes. And this one is more of a collab than most SFM videos - I believe they actually share scene files and whatnot, so there isn't just one artist per shot)
Can you share some of the good ones you ran across from other fandoms? I really just watch stuff from the brony comunity.
As for being involved in one, I've thought about it before, but I don't have nearly the required amount of patience to either wade through 7 seasons of episodes to find the right source material, nor the drawing ability to make custom vectors. I could do stuff using existing vectors that other artists make available, and/or parts that are basically just kinematic typography, but that's still a level of time investment that I'm not feeling right now.