In a Freedom to Tinker posting, Ed Felten writes about AACS, the replacement for CSS to be used for encrypting high-definition video discs:
This scheme limits entry to the market for players, [...] This plan won’t stop filesharing, though
I speculate that the primary objective must be to enforce region coding. I doubt that the studios are really naive enough to believe that people won’t be able to extract player keys, given the dismal history of such “protection”.