Online video leader YouTube on Monday rolled out long-awaited technology to automatically remove copyrighted clips, hoping to placate movie and television studios fed up with the website's persistent piracy problems.

The filtering tools are designed so the owners of copyrighted video can block their material from appearing on YouTube, which has become a pop culture phenomenon in its two-year existence. They also give the owners of copyrighted video the option to sell ads around their material if they want the clips to remain available on YouTube.

To find and remove copyrighted music, YouTube already uses separate filtering tools developed by Los Gatos-based Audible Magic Corp.

YouTube's previous lack of copyright protections for video content prompted Viacom Inc. to sue it for $1 billion US for showing thousands of clips the New York-based company owned.

As YouTube's traffic soared, movie and TV studios became increasingly frustrated with the rampant piracy fuelling its popularity, though YouTube said it has followed copyright laws by removing protected video upon request.

Studios' exasperation with YouTube escalated as other popular websites introduced filtering technology in recent months to prevent copyrighted material from being uploaded.

YouTube's critics have argued that the site turned a blind eye to flagrant piracy so it could show more appealing material to build its audience and pump up its value. Google prized San Bruno-based YouTube so much it paid $1.76 billion US to buy the site 11 months ago.

YouTube has been working with Google engineers ever since to develop the tools needed to flag copyrighted video, said David King, a YouTube product manager.

Google and YouTube executives began promising the new copyright protection technology six months ago.

"It has taken until now to get it right," King said Monday.

Working with copyright owners

It's still too early to tell how YouTube's new filtering system will affect the seven-month-old Viacom suit, said Mike Fricklas, Viacom's general counsel.

"We are delighted that Google appears to be stepping up to its responsibility and end the practice of infringement," he said Monday.

YouTube now needs the co-operation of copyright owners for its filtering system to work because the technology requires copyright holders to provide copies of the video they want to protect so YouTube can compare those digital files to material being uploaded to its website.

This means that movie and TV studios will have to provide decades of copyright material if they don't want it to appear on YouTube or spend even more time scanning the site for violations.

"We really need the content community to work with us," King said. "We need them to help us help them."

Early tests encouraging

Without the help of copyright owners, YouTube has no way of knowing whether material has been legally or illegally posted to the site, King said, because copyrighted video is sometimes provided by the legal owner for promotional purposes.

But YouTube's critics have long derided this defence, arguing that it doesn't take a legal expert to spot some of the pirated material cropping on the website. "If there has been a clip from American Idol posted to the site by Joe Schmoe in Oklahoma instead of Fox, you can be pretty sure it's not supposed to be there," said Rob Gould, vice-president of marketing for Broadcaster.com, a rival video site.

YouTube said it has been encouraged by early tests of its filtering system with nine content providers. Only two of the test participants, Walt Disney Co. and Time Warner Inc., were willing to be identified.

Messages left with Walt Disney and Time Warner weren't immediately returned Monday.