GosuGamers notes that Valve has quietly removed the requirement of a beta key for Dota 2, though this is not the case for those playing the MOBA game in China. Sure enough, checking on the game's listing on Steam included the message: "You already own Dota 2." Thanks Videogamer. Update: Apparently there was confusion here with spectator mode, and keys are still required to play the game. Apologies for the error.