Hollywood screenplay consultant details the five must elements and analyzes outer motivation for the hero, story selection and structure, character development, writing effective scenes and how to sell your work. Norelco
This is a pretty good audio seminar which gives some insightful pointers on how to structure a screenplay and (of course) how to make it commercially viable. As opposed to the other screenplay writing book I've read (Save the Cat!), this seminar gets a little deeper into the actual writing of the screenplay, as opposed to just the preparation and structure. It's definately worth an hour and a half of your time!