can i buy music and videos using my Apple TV? I cannot find the ability to buy a song or video on my Apple TV

You can listen to purchased music through the Apple TV set-top box (they will appear in your library in the Music app), but you will have to do the purchasing on another device. As a streaming device, it has some Apple Music subscription features built-in, where you can add favorite content to your iCloud Music Library.

Similarly, you can view purchased music videos, same as music, or watch any available clip as part of an Apple Music subscription.