First came “Iron Lung,” a video game adaptation self-financed and distributed by YouTuber Markiplier that stunned the box office with a massive haul . Three months later, “Obsession,” a low-budget project from 26-year-old YouTuber Curry Barker, pulled off the rare feat of growing its box office take by 39% in its second weekend in theaters. This weekend, A24’s “Backrooms” — from 20-year-old YouTuber Kane Parsons — grossed a record-breaking $81.4 million in North America and $118 million