Film-makers must act quickly to prevent online piracy hitting the movie industry as hard as it did the music business, actor Morgan Freeman said.
Freeman said he expected smaller film firms to tackle movie piracy
"It is too late when the public is two or three steps ahead of you, and then you are playing catch-up," he said.
Independent film firms were likely to develop the technology to protect new movies, he told Cannes film festival.
Major studios seemed relatively unconcerned about their movie libraries being shared online, Freeman added.
He said major studios seemed more concerned about preventing piracy of new movie releases rather than their back catalogue of films.
Yesterday a "work print copy" of the final Star Wars film, Revenge of the Sith, was leaked onto an internet file-sharing network just hours after the movie opened in cinemas.
A tracker site showed more than 16,000 people were downloading the film on Thursday afternoon.
Earlier this year the European Film Piracy Summit in London was told that movie piracy cost the industry $7bn (£3.8bn) in 2003.
Pirate copies of Revenge of The Sith have appeared on the internet
The Million Dollar Baby star, who won the best supporting actor award at this year's Oscars, said digital technology can bring many benefits - such as downloading films onto a PC and playing them in different rooms of the home.
"One of the things that is terrifying the industry about digital content is that once it gets into the home, what happens to it?" Freeman said.
He said the spread of faster broadband internet connections would make life harder for the movie industry.
While movies require far larger computer files than music, broadband and increasingly popular file-sharing programmes like BitTorrent make it increasingly easy to handle the information.
"Some government entities say that if it's on the internet and accessible, then how can we call it piracy?" Freeman said.