here are the latest set of urls for the apple 4k sdr videos/screensavers ( https://9to5mac.com/2018/09/17/tvos-12-features/ ) which includes the nasa/ISS space flyovers:
the url was found here:
JohnCoates/Aerial#463 (comment)
quote:
"The format changed somewhat; you need to extract the JSON out of here https://sylvan.apple.com/Aerials/resources.tar. The JSON includes the URLs to the videos and the time markers for the tvOS 12 captions as a dictionary, keyed by time. The values of this dictionary are keys which can be found in the strings plists."