Hey alitural,
Take a look at this post to see if the solution by Max P. works for you.
Would you also mind simplifying your test case so I can reproduce the issue in a blank project as well?
In general, most people try to Play() the movie on BeginPlay, but that won’t work, because the movie is likely still loading. You need to use the OnMediaOpened event to get notified when the movie finished loading and then call Play() from there.
Another common problem on Windows is that people are chaining multiple MediaPlayer commands, i.e. Rewind → Play → Pause that will most likely break the player’s state machine. A workaround for right now is to add Delay nodes in between the commands, i.e. Rewind → Delay → Play → Delay → Pause this will give the player some time to process the commands.
With that said, our engineers are aware of this issue and we are working hard to get it resolved. Let me know if you have further questions or need additional assistance.
Thanks,