The fuzzy video, shot by a worker on the floor of a Carrier factory here in the American heartland last month, captured the raging national debate over trade and the future of the working class in 3 minutes 32 seconds. “This is strictly a business decision,” a Carrier executive tells employees, describing how their 1,400 jobs making furnaces and heating equipment will be sent to Mexico.

Workers there typically earn about $19 a day — less than what many on the assembly line here make in an hour. As boos and curses erupt from the crowd, the executive says, “Please quiet down.” What came next was nothing of the kind. Within hours of being posted on Facebook, the video went viral. Three days after Carrier’s Feb. 10 announcement, Donald J. Trump seized on the video in a Republican presidential debate and made Carrier’s move to Mexico a centerpiece of his stump speeches attacking free trade. READ MORE