I own a bunch of digital movies between Amazon, ITunes, Vudu and my local cable provider. I've always wanted to be able to consolidate them in one place. Maybe I'm late to the game, but I came across Movies Anywhere yesterday. They have apps on Apple and Android they have an app on the firestick. I was able to combine my ITunes, Vudu and Amazon libraries all in one place on all my family's devices. The only one I can't get in yet is our FrontierTV cable. Thought this might be helpful for some of you too.
