Sorry, but I can't remember anyone who allready got FMV to run in a homebrew game or demo.
This is because we have no library and not enough time to port a video codec to saturn.
OK, there is an MPG library available, but I think it is only supposed to be used with the VCD cartridge plugged into saturn. I don't have such, but as soon as I got one, I will try to get it to run.
Other people tried to replace FMV in games and succeeded, but there are many different codec versions out there and to incorporate this into your own game is not neccessarily possible.
But many games that use FMV got a special playback executable, that includes the player. If someone could rip it like they ripped Death Tank, it could be used.
Another approach is to port a codec. There is a CinePak library out there like it was used in Saturn games. Also there is an open source codec called VP3.2 from On2 that is related to the duck codec used in games like Deep Fear.
It would be neccessary to handle with the stream library, but haven't done that right now.
You see it would take some work to use FMV in homebrew games.