The new version of Windows Media Player maintains a logfile of all the media (digital video and DVD, digital audio and CD) that each user plays on it, much like a browser’s cache. Unlike a browser-cache, however, WMP talks to a centralized server every time you insert new media and transmits a unique identifier number that could be stored and sold to marketers (though MSFT says they won’t be doing this). And like a history file, the media player’s file can be the source of embarassment if spouses, parents, employers, kids, etc get into it and discover your dirty little viewing and listening habits.
Privacy experts said they feared the log file could be used by investigators, divorce lawyers, snooping family members, marketing companies or others interested in learning about a person’s entertainment habits. It also could be used to make sure users have paid for the music or movie, and have not made an illegal copy.