Hi Grantke26,
Thanks for posting in Apple Support Communities.
We understand that your external display is having trouble play video. To address this behavior, disconnect and reconnect the cable or try with a different cable to determine whether the cable is the issue. Some of the steps from If your external display is dark or low resolution - Apple Support could be helpful.
If your Mac can't detect your external display, your external display will be dark. Use one or more of these steps to try again to detect your display.
* Disconnect the display from your Mac, then reconnect it. It might help to turn off the display first.
* Put your Mac to sleep, then wake it. On Mac laptop computers, you can close the lid for a few seconds, then open the lid again.
* Choose Apple menu > System Settings (or System Preferences), then click Displays. Press and hold the Option key to show the Detect Displays button, then click the button.
* Restart your Mac. If you can't restart your Mac, press and hold its power button for about 10 seconds to turn it off. Then press and release the power button to turn it back on.
Regards.