The problem has been widely reported. There does not seem to be a easy fix, other than stop using VLC as the default video player.
(This is not only with Windows 10. And it is not a new problem, just new to me.)
Here is one of many reports I could not understand.
https://forum.videolan.org/viewtopic.php?t=11616Found another post which worked for me. Go into the preferences,then video>output module(make sure that advanced is checked at the bottom)>scroll down and select quartz video.
Anybody here know more about t his issue?