My music videos no longer play
I am using an iMac, running Sierra, 10.12.6. and iTunes 12.8.0.15. My music videos (purchased from iTunes) no longer play. I can hear the music, and a mini player shows up in the menu bar. The mini player can be made into a tiny player on the iMac, but the video is not playing, no motion, just the music. Muffled. Anybody know what's up?
iMac, macOS Sierra (10.12.6)