Yes even if you get them working on your machine there is no guarantee they will not fail else were anyways.
How i got mine to work was to reformat them from mp4 to a simpler version of mp4 or even re-record them thru vlc. (mp4 is completely broken as far as i can tell at least on my machine.) then convert them thru ffmpeg to WMV using the script show in the example on the posted link for converting files via ffmpeg. I was also playing and stopping it manually which obviously introduced some additional delay.
Hopefully we can get the vlc player libs in monogame the one guy does have a example of how to do it with winforms which i suppose isn’t too far away from doing it with monogame and as he stated the new vlc libs aren’t stable enough yet to commit to it.
If one had the time to concentrate on it or one was already knowledgeable on how to do it quickly you could probably get a basic version working, i am unfortunately not.