US election: Oprah Winfrey, in a Convention debut, calls Kamala Harris 'the best of America'

Winfrey, a billionaire media mogul who built her career in Chicago, had never before spoken at a national convention. Her speech was carefully kept under wraps by Democratic organizers, including a cloak-and-dagger act during rehearsals in which one of the most famous women in America crept into the United Center wearing a hat, sunglasses and a face mask.