The purpose of DRM is not to prevent copyright violations. The purpose of DRM is to give content providers leverage against creators of playback devices.
Browsing: Mike Masnick
True Purpose of DRM: To Let Copyright Holders Have a Veto Right on New Technologies
Veoh Wins Legal Case Against UMG But Collapses Under Legal Fees
Veoh was a YouTube-like site, funded by Hollywood insiders like Michael Eisner, but who got sued by Universal Music Group, claiming copyright infringement (using more or less the same theories used by Viacom against YouTube)