Andrew at the Vuurwapen Blog has just posted a video on using a camera to help improve your shooting. He gives some tips on what sort of video camera you should buy as well as technique. Capturing your shooting on video will let you see where you are making mistakes in technique.
Long before there were digital video cameras, I had been given the same advice by fly casting instructor Macauley Lord about using a video camera to improve my fly casting. Improving technique is improving technique. It doesn't matter if it is handgun shooting or fly casting. It is interesting - long before I knew what dry fire practice was, I knew how to practice doing a double haul without a fly rod in my hand. It is still all about building muscle memory.