For months, Google has responded to complaints by media companies that it is working to create state-of-the-art technology to filter copyrighted videos.
Media companies have argued that existing technologies were already working to filter out pirated content on other video-sharing sites.
Google had been using technology provided by Audible Magic of Los Gatos to identify copyrighted music.
Dubbed "YouTube Video ID," the system creates an abstract image of copyrighted videos and compares that to similar images that are extracted from videos uploaded to YouTube.
While the filtering system began operating in test mode on Monday, the average YouTube user is unlikely to notice anything different - at least in the near future.
That is because Google needs copyright owners to submit copies of their material to the Google database.
Copyright owners who give Google copies their content will have the choice of blocking content if it is uploaded without their consent or choosing to leave it on YouTube for promotional purposes. In that case, they will have the opportunity to make money from advertising provided by Gogole.