Is there a list of Apple TV 4th gen screen saver images?
The fourth generation Apple TV screen saver is composed of QuickTime movie files. You can see the JSON file that Apple TV loads them from at the following URL.

http://a1.phobos.apple.com/us/r1000/000/Features/atv/AutumnResources/videos/entries.json

There are versions of the screen saver for Mac and Windows, not developed by Apple, which you can download at the below links.

https://github.com/JohnCoates/Aerial/releases/

https://github.com/cDima/Aerial/releases/