He got frustrated when Stein asked him several times how life began and repeatedly said "I don't know."
he may have seem frustrated because it's a really fucking stupid question. Lets look at how you and ben stein are stupid. Dawkins is a biologists, not a abiogenecist, nor does anything with origin, thus asking a layman like Dawkins this question is absurd to begin with, expect the answer to be the same (i think it was fine however). Then lets look at the question, if you and stein were educated on origins you would know the theories and the fact that no one knows how life began at the moment. We can create life, but we are unsure of how it happened on earth, thus the question is stupid. So he doesn't fucking know, no one does, so why badger the man with an unintelligent question? are you that stupid, that rude? that uneducated about the person you are talking to?
also, admittance that he doesn't know doesn't make your position true, you seem to take a shadow of doubt and turn it into a glimmer of hope of sorts, sad knowing your reality. It's called god of the gaps, dawkins says i don't know because he is honest and he doesn't no one does, not you not me not anyone. life has been created life in many ways in a lab, would you like proof? however, we still aren't exactly sure, who cares? don't just make shit up morons.