Young audiences turned out in droves to movie theaters around the country this weekend. It wasn’t for the big budget “Star Wars” movie, “The Mandalorian and Grogu, ” which fell sharply in its second weekend, however, but for a small budget horror from a 20-year-old first-time filmmaker that began on the internet. “Backrooms,” released by A24 in 3,442 locations in the U. S. and Canada, made an astonishing $81. 5 million in its first three days in theaters, according to studio on a...