I am in at the in-laws in the middle of rural France. We want to watch Zoolander because my mum in law has never seen it and she loves silly films.

We have:

A tv with usb and hdmi inputs
2 iPads, a samsung android pad and 2 iPhones
An internet connection which isn't consistently fast enough to stream movies
A wifi network that doesn't reliably reach the tv
A pc connected to the internet
No lightning or android to hdmi cable
An amazon firestick
An amazon account
A usb drive

No shops are open

How can we legally buy Zoolander, download it and watch it on the tv tonight?

I assumed we could buy the film on the PC, copy it to usb and watch it on tv. This should be easy, but somehow it seems impossible unless we pirate the film, which isn't the way we want to go.

I can't believe in 2015 there's no way to legally download a film to a usb drive. What am I missing?

deleted. doesn't solve your problem.

What rights systems do is ensure that only the purchaser can play the file.

If a person could download (for a fee) a film that could be decoded on another device then the file would clearly need to have NO copyright protection.

They do have copyright protection, thus there is no way it can be done.