This is what Video Game Commercials Teach Us about Censorship

After I watched the most recent commercials for Assassin's Creed 2(see video), I noticed something about them. In a game about an assassin whose job is to kill, the commercials do not depict a single death. Why can I turn on CSI and hear the tale of the Las Vegas Stripper Rapist/Murderer/Cannibal but a commercial cannot show a virtual historical person being killed. Perhaps more confusing is that I can watch a sword make a bee line for someone's chest but the camera will cut away right before the contact. Is there anyone out there that doesn't know what's coming next? Has censorship gone so far as to forbid virtual death in a commercial? Or is it simply picking on video games "Up next on CBS: the crime lab at CSI:Miami tackles the grisliest case of child rape and murder they've ever seen." Why can we tease people with CSI, Law and Order, 24, etc. and the murders of real life people but we can't show a historical figure being killed by an assassin (many of the targets in the game are real life historical figures killed under mysterious circumstances, perhaps by an assassin)? Or is it simply alright to show corpses but not someone actually being killed?