NEW YORK (AP) -- The premiere of a virtual reality short by Oscar-winning director Kathryn Bigelow was already a high-profile event at the Tribeca Film Festival on Saturday night. And then Hillary Clinton walked onstage. Clinton was an unannounced panelist, there to discuss the scourge of elephant poaching - the subject of Bigelow's eight-minute film "The Protectors: Walk in the Rangers' Shoes," about park rangers trying to save elephants in Garamba National Park in the Democratic Republic of the Congo. She spoke about her work to save elephants from poachers slaughtering them for their ivory tusks, both as secretary of...