To "own"? Let's not kid ourselves here... there's no real ownership involved unless there is a way to get DRM-free files in 720p off the device using anything other than your eyeballs. I seriously doubt there is, which makes this just a really expensive rental service. I'm sure there are already lots of services which feature renting movies from all 6 major studios while taking your money and laughing about it.
Really - your eyeballs can get files off a device? So should I call you Jordi LaForge?
Not that I would use this service (I prefer having the physical media), but if I get to d/l it to my computer, and it resides there as long as I so choose to keep it then I own the right to view the movie as much as I want. I don't own the movie, that ownership resides with the company that released it...but I own the right to view it. Same thing if I buy a dvd from a store. It's about preference. My friend prefers to have his movies on hard drive, i prefer to keep it on disk.