An Amazon Prime subscription comes with a ton of perks, and one of those is Prime Video. In my experience, it doesn't have nearly as much selection as Netflix or Hulu, and I personally only really use it to watch The Grand Tour. But back to the topic at hand: Prime Video now has over 100 million installs on the Play Store.
In comparison to competing video subscription services, Prime Video is pretty squarely in the middle. Netflix has over 500 million downloads, while Hulu is still in the 10-50 million range. It is worth noting that Prime Video is pre-installed on some devices, namely Amazon's line of Prime Exclusive phones.
You can download Prime Video via the Play Store widget below.