Just wanted to post a followup here since this user is reporting the same issue I was. I had the bug actually pop up for me during some playtesting. Here is the console info in case it is helpful :).
Viewing post in Ritter Title Movie Plugin (RPG Maker MZ) comments
I haven't found a way to replicate this error yet, do you know how to get it to occur? I do see in the code how this *could* happen but it would be best if I could see it happen myself. I'll be releasing an update for testing purposes soon, once I nail down and am satisfied with the logic applied to prevent this kind of issue from occurring. I'd rather not blindly apply a patch that I assume should work and have an event where the video playback doesn't function properly when this issue would occur.
Unfortuantely no I don't know of a way to replicate it. I can only say that a player reported to me that it happened when he had the game minimized for awhile.
When it popped up for me, it just randomly happened when I booted up a playtest. Didn't seem to be any rhyme or reason for it. I'll experiment a bit today and see if I can replicate it.