Our moderators preview the PBS NewsHour/POLITICO debate

The PBS NewsHour/POLITICO Democratic debate airs Thursday night from Los Angeles. Three of the debate’s moderators, Judy Woodruff, Amna Nawaz and Yamiche Alcindor, join John Yang to discuss controversies around the debate qualifications and candidate diversity, how they have prepared for the big event and what recent polling says about the likely Democratic voters who will be watching.