Whenever I hear statements like that (that the musical/movie industry is growing thanks to piracy, etc), the only logical question for me is - why are they fighting it so hard then?

I mean, they are fighting the various P2P sites and users for years, spending large amounts of money on various legal fights and lobbyists. The wouldn't do this if it really didn't hurt their sales.

People can say "they are doing it because they are stupid". Well, maybe they are, but they also have far better statistics than we have. They know far better what is hurting their sales.

I am not really arguing for copyright industry here, but I am just saying - if it didn't hurt them, they wouldn't be fighting it so hard.

People talk about the "business model" of the film and music industries.

But they have a "moral model", which is to present copyright itself as a moral proposition. Everything about why it is hard for us to stop the never-ending creation of new laws and international treaties that attack freedoms of computer use and internet use is due to this moral model.

It follows that empirical studies proving the "harmlessness" of piracy are largely irrelevant.

...like rational, scientifically backed arguments, will burst MPAA/RIAA's bubble. For anyone on the outside, the findings in this article are common sense. So is the fact that MPAA/RIAA's business model is severely broken. Yet, that doesn't matter when you have Washington on your payroll. Unfortunately.

What is the logic behind waiting to release Hollywood movies outside of the US?

US Movies are often released outside of the US to see how well they go, so that an appropriate marketing spend can be done. Various small countries, and small towns will go first. Like New Zealand.

If the movie does ok, then that is more evidence for the investors to ok the massive marketing spends. But if their trial marketing fails (and their 10 different versions of it), then the movie will be released changed or released in one of the spare slots; the slots that they need to fill in the movie theatres to keep their quadmopoly(if they don't take up the screens with some crappy movie then some independent might get a shot at a screening instead).

A more relevant question would be how piracy affects movie rentals and DVD/Blu-Ray sales. You can't go out to see a pirated movie, so box offices sales and pirated movies are apples and oranges.

tl;dr

Study tries to find out if piracy has a larger effect in foreign box office returns the longer the length of time between the domestic and foreign release. Answer: Yes.