Kevin decided on a career in content moderation after his YouTube recommendations took a bewildering swerve. In 2021, videos appeared on his feed depicting violent attacks by Boko Haram, a Nigerian militant group. They were raw and gory, and reminded him of violence he witnessed as a child in Nigeria.One day, the videos disappeared. Who did that?, he wondered. He read online that removing disturbing stuff from the internet was a job — one he could apply for. “I didn’t want people to go through l...