Hi there TJLewis,
Thank you for your effort explaining to me the detailed scenario TJLewis,,
I really appreciate your effort to do so.
It nice to hear that there are still people like you who are obedient to the law.
Upon reviewing the subject on legality of downloading movies once you purchase.
Downloading movies is illegal when it can contribute to the loss of business of the owner of copywrite, meaning if you download the movie on sources other than official sources who are legally allowed to distribute this product.
Second it also becomes illegal when you purchase the movie on an official site legally allowed to distribute the product but downloaded multiple copies and sold it with a profit because it contribute to the loss of business to the owner of the copywrite.
But in your case since you purchase it and download it on an official site legally authorize to distribute the product, it wont be illegal to you to use the product in other device, even if you download it an an external flash drive to back it up because you have already purchased it anyways.
I hope this answer your question
Thank you again for posting this question to us TJLewis,
It was a pleasure providing service to you today
Best Regards,
Anthony De Jesus
Independent Advisor