Hi 1985ns,
Thanks for the post! As we understand it, you're having issues with video in the YouTube app on your Apple TV hardware. It's always important to be able to watch videos, and we'd like to see how we can help.
Does this happen with any other apps on your Apple TV?
Have you updated your tvOS version? tvOS 14.3 is the latest: How to update your Apple TV
If YouTube is the only affected app, reinstalling it may help also If an app unexpectedly quits, stops responding, or won’t open.
"Apple TV: Highlight the app on the Home screen, then press and hold the Touch surface until the app jiggles. Press Play/Pause, then select Delete. Open the App Store and redownload the app. Some apps require subscriptions for activation. If you can't activate the app or you don’t remember your sign-in information, contact the app developer."
We hope that helps. Have a good one.