Brandon Tatum, an officer in the Tucson Police Department, shared a video Saturday night giving his perspective on Donald Trump’s campaign rally in Tucson, Arizona — and the disruptive protesters who hurled obscenities at the Republican candidate. Tatum says that as a black man, he did not feel unsafe around Trump’s supporters but was ready to fight protesters in self-defense. He calls them the most hateful, evil people he has ever seen. The demonstrators, who he recalls chanting the phrase “Black lives matter,” used profane language and gestures, leading a mother to cover her child’s ears. One protester, he recounts,...