Robert Mackey at the NYT reports that Chinese art-provocateur Ai Weiwei was in the right place, at the right time, and captured video of “a small group of protesters [who] briefly surrounded the American ambassador’s car” outside the US Embassy in Beijing, pelting it with objects.” Ai Weiwei uploaded the footage to YouTube, showing “that the protesters arrived at the embassy’s gate, with remarkable timing, at precisely the same moment as the ambassador’s car. A line of police officers appeared, running in formation, seconds before the protesters blocked the car.” The incident took place amid widespread protests and acts of violence in China over the status of disputed islands also claimed by Japan.