Ukrainian video journalist Mstyslav Chernov, who was trapped in Mariupol during the onset of the war, documented the events for the Associated Press. On Sunday, he and his team won an Oscar for their documentary on this story. Frontline producer and editor Michelle Mizner  joins host Krys Boyd to discuss Chernov’s first-person account of life under siege, the horrors of a bombed maternity hospital and, ultimately, the power of the press. The documentary “20 Days in Mariupol” is available for streaming.