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Rupert Grint, Daniel Radcliffe and Emma Watson attend the New York premiere of 'Harry Potter And The Deathly Hallows: Part 2.' - 

STEVE CHIOTAKIS: The final Harry Potter movie is hitting box offices around the world reaching the U.S. on Friday. In France, where it just started showing, demand's been so big that Warner Brothers put on a special screening last night in one of Paris' biggest concert halls. It delighted thousands of Potter fans but really upset the French film industry.

The BBC's Rebecca Singer reports.

REBECCA SINGER: When you buy a ticket for the movies in France, you don't just get to see a film. You're also helping support the French film industry. That's because more than 10 percent of every ticket sold is a tax -- money to be reinvested in the country's movie business.

But only movie theaters pay the tax -- venues like the Bercy concert hall are exempt. So by holding the French premier of Harry Potter there, the industry lost out on as much as $35,000 of funding.

Michel Ferry is a film director and producer in France.

MICHEL FERRY: I mean every single people in the chain would have benefited from it. It could be writers, could be directors, could be producers, could be theatre owners.

Ferry admits that $35,000 isn't a huge amount of money, but that it sets a dangerous precedent. It may be a concert hall for Harry Potter. But if you start showing films in stadiums or other venues where the industry doesn't get a cut, Ferry says it could undermine the future of movies in France.

In London, I'm the BBC's Rebecca Singer for Marketplace.