Pretty sure the TOS of AppleTV prohibits exporting the movie - you have a limited license to view it only under the circumstances Apple dictates, in partnership with everyone Apple has deals with. If you want to be able to watch it on other devices, you need to purchase a limited perpetual license in the form of a DVD/bluray.

Now, of course, this depends on the movie having a physical release (which is becoming a bit of a rarity these days), but still, the MPAA has made sure to write ironclad contracts to prohibit watching streamed content the way you want.