TV networks, film studios, and consumer electronics companies are participating in an effort to add a watermarking technology to digital television broadcasts by March that would prevent consumers from trading movies and TV shows online, either through peer-to-peer file sharing networks such as Gnutella or through personal video recorders such as TiVo or UltimateTV. C|net reports that studios are worried about piracy in broadcast TV content because the signals are not scrambled the same way that cable or satellite feeds are.