It means that the video in question requires a license to play on your computer. The player usually will attempt to contact a website and obtain a license for you.

Many P2P networks are flooded with "videos" or "Files" that require a license to play that are nothing more then bait to lure you to their website. Usually they are not the file they state to be, so use caution.

Music and video files that require a license are generally not a bad thing. But like everything else abuses can be found.

For further information on licenses and limewire see this topic.
http://www.gnutellaforums.com/showth...threadid=42070