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 state in the Obama administration, and later with her family foundation, the Clinton Global Initiative.

"We've got to bust this market so it can't come back," she said of the illegal ivory market.

Before Clinton and the three other panelists were interviewed by Bigelow, the audience donned virtual reality headsets at their seats and experienced - in 360 degrees - what it's like to be one of the 200 rangers fighting well-armed poachers in the park the size of Delaware.