"Scour is Napster with movies," said Jack Valenti, the chairman and the CEO of the Motion Picture Association of America, one of the three plaintiffs in the lawsuit filed in federal court in New York.
Scour, which is best known for its multimedia search portal Scour.net, started the Scour Exchange, or SX, last April.
The software client, once installed, allows users to connect to other computers and download specific multimedia files from each others' hard drives.
Unlike Napster, which only allows the downloading of MP3 music files, SX allows users to swap MP3, video and image files.
That has the MPAA and others up in arms.
"You cannot take property that belongs to someone else and copy it. The complaint sites specific movies that can be found on Scour," Valenti said.
The movie exec claims that he found 25,000 people online and using SX when he connected to look at the technology.
"When 25,000 people are on the site at the same time, you know there is a lot of copying going on," he said.
A look at top download sites confirmed that at least 100,000 users have downloaded the latest version of the SX program.
Movies found on the service include "Gladiator," "The Patriot" and even the "X-Men," which was release six days ago.
A great many songs have also made their way into the exchange, which has led both the Recording Industry Association of America and the National Music Publishers Association to join the suit.
The New York lawsuit marks the latest legal shot fired by copyright owners in their fight to quash what is quickly becoming rampant copying of their wares on the Internet.
Next week, the RIAA will also appear in federal court in San Francisco to ask for a preliminary injunction to stop Napster from facilitating the free trading of music online.
In New York, the MPAA started its federal lawsuit against three New York-based Web sites for copyright infringement because the sites carried copies of a program designed to defeat the encryption on digital video discs.
Among the defendants is the publisher of the underground Webzine 2600, Eric Corley, better known by his nom de Net, Emmanuel Goldstein.
Scour could not be reached for comment.