The new technological weapon is content-recognition software, which makes it possible to identify copyrighted material, even, for example, from blurry video clips.
The technology could address what the entertainment industry sees as one of its biggest problems--songs and videos being posted on the Web without permission.
Last week, Vance Ikezoye, the chief executive of Audible Magic in Los Gatos, Calif., demonstrated the technology by downloading a two-minute clip from YouTube and feeding it into his company's new video-recognition system.
The clip--drained of color, with dialogue dubbed in Chinese--appeared to have been recorded with a camcorder in a dark movie theater before it was uploaded to the Web, so the image quality was poor.
Still, Ikezoye's filtering software quickly identified it as the sword-training scene that begins 49 minutes and 37 seconds into the Miramax film Kill Bill: Vol. 2.