How can I watch videos I've purchased or rented in the AppleTV app?

Minimum Requirements: 

The minimum operating system that you can view your purchased and/or rented content on Apple TV is tvOS 11.0 or higher. 

To watch purchased and/or rented videos on Apple TV: 

1. Open the seller's app and log in if prompted. 
2. Navigate to the Library.
3. You can find your purchases and rentals under the My List tab. 
4. Select a video to play.