Disney, which includes Apple chief executive Steve Jobs as a board member, is the only movie maker to take the plunge into downloading so far.
Other film producers have stayed out of iTunes, in part because they fear that it may cannibalise DVD sales.
Disney chief executive Bob Iger told the Financial Times that digital distribution is "creating more consumption of media".
"The message we deliver to our traditional [retail] partners is that the pie is getting bigger," he said, pointing out that two of the most popular downloads, Pirates of the Caribbean and Cars, are also the company's best selling DVDs.
Disney has also put its television output online and to date has had more than 20 million downloads.
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