Universal Music Group is suing the operators of two video-sharing Web sites, claiming they illegally let users share music videos and other copyright material without permission.

Universal Music, the world’s largest recording company, filed separate lawsuits against Grouper Networks Inc., operator of Grouper.com, and Bolt Inc., which runs Bolt.com. Sony Corp.’s Sony Pictures Entertainment acquired Grouper for $65 million in August, and Universal Music said it may add the film studio as a defendant.