Everyday, thousands of people flock to video-hosting Web sites such as YouTube.com. The sites' content, which anyone can contribute to freely, ranges from clips of presidential speeches to music videos to cats clinging to ceiling fans. Now Universal Music Group, the world's largest recording company, is taking two such sites to court.

On Oct. 17, Universal filed separate complaints in U.S. District Court in Los Angeles against Grouper Network Inc., which runs Grouper.com, and Bolt Inc., which runs Bolt.com, for allowing users to post hundreds of copyrighted music videos and songs without authorization. The suit alleges that both sites played an active role in violating copyright laws by “copying, reformatting, distributing and creating” works derived from music videos and songs owned by the label.

Soon after Universal filed the complaint, Bolt posted an announcement on its homepage, urging users to discontinue uploading music videos.

“We understand the love you have for your favorite musical artists, but Bolt respects the rights of copyright owners such as Universal Music and their artists, and we ask that you please do so as well by not uploading their videos to Bolt,” Jay Gould, the company's president, wrote.

Universal spared YouTube.com from being named a defendant thanks to a licensing deal Universal struck with the video-sharing site earlier this month. Hours after making the deal, search engine giant Google Inc. bought YouTube.com for $1.65 billion.