Have you got a copy of MonoGame source code on your machine?
If you have, would you mind doing some tests for me?
- Change const int retries = 5; to const int retries = 50;
This will tell us if it is a timing issue with content loading. Possibly caused by threading issues as it obviously used to work.
- Display the results of the ffprobe for both wmv and 264
Just in case something in ffprobe has changed which will break the code
- Take one of the videos that didn’t work and remove the audio
Which will tell us if it is a video or audio problem
If you can do that I will try and find the time to do some fixes and maybe get looping working