This is a worst title with the name of Stephen Hawking on, Errol Morris just used this great name to abuse the buyer.
I have a collection of books and DVD by Stephen Hawking or related to him, the latest good DVD I bought here from Amazon.co.uk is "Genius of Britain". This DVD by Errol Morris has more than a half of the run time filled with rubbish from people who know Stephen Hawking like his mother, sister or other neighbors. If you already read the book like me, you'll find nothing interesting in this DVD, on the other hand, if you haven't read the book, be careful : while the book "A brief History of Time" is a major science work, this DVD with the same title directed by Errol Morris is only a piece of junk.
I suggest that Amazon should add some warning in the description about this DVD which has too few thing to do with the best seller.