Please work to enable movie playback from the Apple TV app in MacOS Big Sur.
Apparently since MacOS Big Sur thinks the screen is being recorded while the displaylink app/driver is active, the DRM and HDCP features block movie playback on all monitors including the MacBook Pro’s built in display. Movie playback from the Apple TV app returns to normal upon deactivating/quitting the displaylink app. Of course video files (and YouTube) that are not DRMed play back fine.
As soon as the DisplayDriver driver is active all monitors attached to that Mac (the non-DisplayLink monitors too) can not playback DRM protected content. That really is very inconvenient.
Ben Allan commented
Yes! I'm finding this with Catalina on Apple TV and Disney Plus,
Second on this. It is pretty annoying :(. Netflix in Safari isn't playing too. Chrome seems to not have that issue..