Dumbbell Bench Press and hand position

The video that I was pointed to in your answer (which I had already seen and was great) talks about arm position rather than hand position.  I mean what is the difference both in terms of safety vs development ability (for lack of a better term) when your hands are facing each other (natural grip) vs facing forward (or what I would call normal) during the press.  

The arms should be at a 45 degree angle from the torso. i explain in this video. http://www.workouttrainer.com/home/videos/wt0-7workout-101-dumbbell-position