Is an Amazon Video Purchase really a purchase?

I have been buying Amazon videos so that I can download and watch them on my old iPad. The latest release of the Amazon Prime Video app no longer supports IOS 9.3.5 which is the last version of IOS for my iPad.

I can no longer watch my purchased videos on my iPad. My thinking is that Amazon has denied me fair use of my purchase. If I wanted to watch things on my computer, which I can still do, I would not have purchased the items.

This just seems wrong to me and I'm considering going to small claims court to get a refund. Any experience or thoughts about this?

[edit to clarify title]