But they have DRM and if apple's itunes can't auth, you can't watch. If you don't believe me, try to play it on a new computer or de-auth your existing one. After awhile, the authentication on the devices dies.
I cache iTunes content locally because I've had music disappear in the store before that I bought. (prior to them going drm free on that) The album still plays with my files but apple doesn't have it anymore. I've never seen that happen with video, but it's certainly possible.
If you have Disney content, you can get their app and then connect it to Google Play and iTunes. It gives you purchases in one on the other so you get a backup with an independent service.
The new problem I have is storage. I'm at 5TB of iTunes content and apple got rid of internal drive bays. There is no mac to buy that can hold them and I'm hitting the limits of external hard drive enclosures too. Whatever I buy, I have to have a bigger drive for time machine to back it up too. (mac mini drive + ITMS drive == 5.5TB just for one snapshot)
external raided enclosures get rather pricey.