Apple TV stopped working on Samsung tv. Works fine on iPad and other tv

The solution to the Apple TV app not playing videos reliably on Samsung TV:

1. Navigate to Settings > Support > Self Diagnosis > Reset Smart Hub.
2. Enter the PIN for your TV. Default is 0000.
3. After the smart hub reset, press Home and then select Setup.
4. Follow the on-screen instructions to set the TV up.

This is a faff and takes 20 minutes but it cured the bug, and when testing, the previously unplayable or freezing videos were then working.

If the Apple TV app misbehaves on your Samsung smart TV, then consider these troubleshooting steps from Samsung Support: What to do if an app is not working on Samsung TV - Samsung Support

1. Cold reboot the TV,
2. Update the TV system software, if available,
3. Delete and reinstall the misbehaving app (if deletion is supported for that app),
4. Reset the ‘Smart Hub’ (like a factory reset for the apps part of the TV).

If you need further assistance after that, please contact Apple Support.

Thanks for this addition.