There is no Google Play App for the original Apple TV, but you can still watch Google Play movies using Youtube. When you do a search in Youtube, any movies that you have purchased in Google Play appear in the Youtube search results. So even though Apple TV does not have a Google Play App, you can still purchase or rent a movie from Google and watch it on your Apple TV. Google suggest a way to do it by streaming the movie from your phone, but a far better way is to watch the movie directly in Apple TV via the YouTube app. Here’s how.
(The Google Play Store has Rotten Tomato Ratings as well as extra payment options such as ‘Use Telstra Pay’.)
The movie you will appear in the search results. Click on the movie. If it’s a purchased movie you can watch it. If it’s a rented movie you’ll get the usual warning about the rental time, and you will need to click yes to confirm to start the rental.