I'm sure others can go more in depth, but the first thing I noticed was a lack of a pushaway, which resulted in you having to force your arm to swing back and then forward again.  You had to bend your elbow a bit to accomplish this too, which can hurt consistency and accuracy.  Push the ball out further away from your body in a line straight underneath your shoulder.  Then let the ball fall into a swing from there.  You should be able to relax your arm a little more and free up your swing.  This should give you more accuracy, possibly more speed as well, and it will feel more comfortable and natural.

I keep my hand and arm both very, very relaxed as well.  Using a pushaway lets me keep my arm swinging consistently straight and keeps my timing the same every ball.  When I'm losing accuracy, it's usually because I'm getting lazy with my pushaway and stopping it a little short.