MySpace plans to offer entertainment companies and other copyright holders an online tool to find and remove unauthorized videos on the popular social network, which is moving quickly from Web maverick to a mainstream platform for online advertising.

The latest move to rid the site of illegal material is certain to please media companies, which include MySpace parent News Corp., at the expense of users who often include copyrighted songs and video in their own postings.

MySpace on Friday said in a release that it's testing the tool with Major League Baseball and the Fox Broadcasting Co., which is also owned by News Corp. The tool would enable copyright holders to find and flag infringing video, which MySpace would then remove from the site.

MySpace declined a request for an interview, but copyright litigation lawyer Greg Gabriel said the company appears to be going beyond what's legally necessary to protect itself. MySpace follows the federal Digital Millennium Copyright Act to the letter by way of a "notice-and-takedown" policy, which means the site removes protected content at the request of property owners.

"What they're doing is streamlining the process for copyright holders, but I don't think this was something they were legally obligated to do," said Gabriel, who works for the Los Angeles law firm Kinsella Weitzman Iser Kump & Aldisert. "But they may be doing it to ingratiate themselves to copyright holders."

In appeasing media companies, MySpace could be setting itself up for making content deals to keep the kind of entertainment users love on the site. MySpace owes its popularity in large part to music fans who use the site to share and promote their favorite tunes and bands.

"There's no question MySpace is interested in creating a safe environment with the purpose of copyright holders themselves being able to offer legitimate streaming or downloading of their own programs," said Todd Chanko, analyst for JupiterResearch.

Just as important, that "safe environment" is necessary to draw advertisers, which don't want their brands displayed next to illegal content. In August, Google signed a $900 million deal with News Corp. to distribute advertising on the latter company's Web properties, including MySpace.

While some MySpace users could become angry at seeing their favorite videos disappear from the site, Chanko doesn't believe the site would suffer any major defections. Unlike video-sharing site YouTube, which is also working with media companies to remove unauthorized material, MySpace is not dependent on video alone. Many users use the site primarily as a virtual gathering place, a kind of Internet coffee shop or bar.

"Some people will be pissed off, but I don't think it will drive down the user base significantly," Chanko said.

Not alienating its users is critical to MySpace as the site's phenomenal growth inevitably slows. MySpace may already be showing signs of near saturation. From August through October, the site remained at about 49 million unique visitors, with a dip to 47 million in September, according to Nielsen/NetRatings. Year to year, however, the site grew 140%.

MySpace did not say how long it would take to rollout the tool, which would only be available to companies that showed they were legitimate copyright holders. Because technology capable of searching actual images in a video is not yet ready for primetime, Chanko believes MySpace will depend on searching tags and metadata in video files to look for copyrighted material, a methodology that's sure to miss a significant portion of unauthorized content.