Police have arrested Anton Dunn, a 42-year-old New Yorker who uploaded videos to YouTube and other sites in which he wears a black mask and calls himself “Trashman.” In the videos, Mr. Trashman announces that he’s managed to poison “millions of bottles of baby food” with cyanide. Gerber, the company he names in his threats, says it’s found no evidence that any food has been tampered with.