Here is the apk for Amazon prime video which has been ported from the Nvidia shield and works on the Mi Box without any issues.
Link : https://drive.google.com/file/d/18eWwZjfW9aPSixQeajXmgrkqHnZsWizj/view?usp=drivesdk
Proof : https://drive.google.com/file/d/1uimKcPdw9LQG5KlNSnKGIbJQJIbPL-zU/view?usp=drivesdk
Any good soul out there wiling to send me Filmstruck .apk file for Android TV?
https://play.google.com/store/apps/details?id=com.turner.filmstruck&hl=sr
https://play.google.com/store/apps/details?id=com.amazon.avod.thirdpartyclient&hl=en
Though on my MiBox it's buggy. Often won't show indicator of the cursor position. Playback won't last more than a minute before FC.
Edit: to clarify, the link is for general Prime Video app on Playstore. It used to say not compatible with ATV but you can push the app to an ATV now.