Initially the female rejected the male, but the male then showed interest in her.  He began to do some initial tongue flicks and crawling along the female's back.  He then made a few jerky motions and the tails locked.  Male snakes have two hemipenes that lie inverted into the tail.  When mating is immenent one of the hemipenes fills with fluid, everts and enters the female's cloaca.  Because of the shape of the hemipenis it is difficult for the female to escape, should she choose to do so.