Prime writes on its site: “Many first-party video subscription titles are also available for download on compatible devices such as Fire tablets, Android and Apple iOS devices.
“You can download available titles to only two devices at one time.
“If you have already downloaded a title to two devices, you need to delete it from one of them before downloading it to another device.
“Depending on your location, you can have a maximum of either 15 or 25 total titles downloaded across first-party and third-party video subscription titles at a time across all devices associated with your Amazon account.
“While not all first-party video subscription titles are available for download, the same videos may be available for rental or purchase from Amazon Prime Video, which can then be downloaded to compatible devices.”