Why are some sites restricting access to non-US viewers?

Factual Questions
1

I’m eagerly anticipating the 2nd season of Masters of Horror, a series produced by Showtime. (The 1st season was aired by Bravo on the UK, which showed the whole series, including the notorious episode which Showtime didn’t have the balls to show.)

However, to my point. Seeing the link below:

Masters of Horror

I proceeded to the Showtime site to catch a preview, only to be greeted by a message saying, ‘Sorry, this is for US viewers only’, or some such thing.

What gives? I’ve seen this on other media sites. There’s no issues of copyright, it’s only a preview, for God’s sake! Why do they do this?

2

The BBC does the same thing with their broadband content to non-British viewers. Here’s their explanation, which is probably similar for Showtime:

“Broadband content is expensive for the BBC to stream. The BBC has therefore decided to limit access to the BBC broadband content to UK residents to ensure best value for the UK licence fee.”

It’s a cost-saving measure, in other words.

3

Isn’t that the free broadband content? Can’t international viewers subscribe to and pay for the BBC’s broadband content?

4

I remember the Stargate SG-1 site was restricted to US only after us foreigners posted spoilers cos we were seeing episodes before they aired in America…