Here's how it went down, per several witness: Grim and Watters were among a group located in a heated tent just outside the main party area. The two apparently don't have a personal relationship, but Grim realized who Watters was and recalled a beef he had with the "O'Reilly Factor" correspondent that dated back to 2009, when Watters, known as an "ambush journalist," had engineered an on-camera confrontation of writer Amanda Terkel, now a HuffPo colleague of Grim. Terkel's account of the incident was headlined "I Was Followed, Harassed, And Ambushed By Bill O'Reilly's Producer."