Is NAFTA a success story or damaging policy?

A one-day summit in Mexico between President Obama and his North American counterparts marked the 20th anniversary of NAFTA, a trade agreement designed to eliminate cross-border duties and other barriers. What's the legacy, effect and the future of NAFTA? Jeffrey Brown gets debate from former U.S. Trade Representative Carla Hills and Lori Wallach of the Public Citizen's Global Trade Watch.