Will we be wiped out by machine overlords? Maybe we need a game plan now

Computer superintelligence is a long, long way from the stuff of sci-fi movies, but several high-profile leaders and thinkers have been worrying quite publicly about what they see as the risks to come. Our economics correspondent, Paul Solman, explores that. ACTOR: I want to talk to you about the greatest scientific event in the history of man. ACTOR: Are you building an A.I.? ACTRESS: Do you think I might be switched off? ACTRESS: Why is it up to anyone?