Dismissing privacy concerns, a federal judge overseeing a $1 billion copyright-infringement lawsuit against YouTube has ordered the popular online video-sharing service to disclose who watches which video clips and when.

U.S. District Judge Louis L. Stanton authorized full access to the YouTube logs after Viacom Inc. and other copyright holders argued that they needed the data to show whether their copyright-protected videos are more heavily watched than amateur clips.

The data would not be publicly released but disclosed only to the plaintiffs, and it would include less specific identifiers than a user's real name or e-mail address.

Lawyers for Google Inc., which owns YouTube, said producing 12 terabytes of data — equivalent to the text of roughly 12 million books — would be expensive, time-consuming and a threat to users' privacy.

The database includes information on when each video gets played, which can be used to determine how often a clip is viewed. Attached to each entry is each viewer's unique login ID and the Internet Protocol, or IP, address for that viewer's computer.

Stanton ruled this week that the plaintiffs had a legitimate need for the information and that the privacy concerns are speculative.

Stanton rejected a request from the plaintiffs for Google to disclose the source code — the technical secret sauce — powering its market-leading search engine, saying there's no evidence Google manipulated its search algorithms to treat copyright-infringing videos differently.