nostr:npub1e2p79z2nl0xkd2n0qy52wwvej2y3j8ps28nl4utfsw0apsnc586seraqmc 

While there almost certainly is a technological solution – most likely a complex and fiddly technological solution – I see a major problem with your question that probably means doing so is illegal.

Its that word you use: 'purchased'.

I think if you read the fine print you'll discover you did not actually *buy* the movies. You bought a license to watch them using Amazon's app or website and have not purchased a right to keep a copy you can watch without them.