Just googled this - turns out the chick is a "performance artist" trying to get people to react in this video. She didn't look to me like the garden-variety nutjob you see on the subway - too well dressed, and she obviously came prepared with a knife and cutting board.
He just wanted attention. Some policemen came and he's just smiling and bumbling to them and just talking and such. I felt like knocking him the fuck out.