The Arctic is becoming more accessible due to climate change – as the battle over oil and mineral resources heats up. Lesley Stahl has the story. Bill Whitaker learns not to mess with Mary Quin – as she recounts the story of her kidnapping by militants in Yemen. “The Birth of a Nation” has generated a huge amount of Oscar buzz – but for actor/director Nate Parker – it’s his past that’s making headlines. Anderson Cooper has his story.