“There’s one way this is going to go,” he told the man. “You’re going to end up knocked down unconscious.”Over the more than two years he helped produce and publish videos for Mr. Robinson and others, Mr. Robertson learned how making clever edits and focusing on confrontation could help draw millions of views on YouTube and other services. He also learned how YouTube’s recommendation algorithm often nudged people toward extreme videos.“It meant that we did more and more extreme videos,” Mr. Robertson said.Caolan Robertson grew up in Ireland, and after his parents divorced, he …
