I am a big proponent of getting training from a qualified and good instructor as often as possible. One of the things that a good instructor brings to the table is a set of eyes that can see what we are doing wrong and the experience and knowledge base to know how to fix it. As the shooter, we just can't see everything that is going on with our bodies, and we shouldn't. Our focus should be on shooting the gun.The truth though is that we cannot afford to have an instructor with us every time we are at the range practicing.
This is where video comes in. Since we can't have a skilled instructor by our side every minute of every range trip, the camera serves as our third eye and lets us see things from a different perspective. Not only that, but it might even let us see things that we normally wouldn't see in real life even if we were able to actually watch ourselves by slowing the video down. (A side note, this can probably be a learning tool for instructors too)
Agreat example is the shotgun video I posted the other day. My shoulder transition isn't perfect, but when I did it, I felt pretty good about it. Now I know not only was it not perfect, but I know where I need to improve to make it perfect. Without video I can shoot a drill and not get the result I want and know that I am screwing up somewhere, but that is about it. As an example, my reloads need a lot of work, but all I know from a shooter perspective is that they are not as fast as I want them to be. With video I can pin point what things I am doing wrong and then develop and plan of attack for correcting those mistakes. Basically I cannot fix it without knowing what is wrong with it, and video lets me see all the little nuances that might be wrong.
The same applies to match video. I like to have someone video all of my matches when possible and then I can review the video and see where I need improvement. Things like being aggressive around cover, moving the feet faster, etc. I only shoot club level matches so far and so sometimes I place pretty decently because the depth of competitors isn't that great and if I walk away from a match and look at the score sheet and think "Hey, I did pretty good!" I would never know all the areas that I really need improvement. Video of my shooting in the match lets me see all that, usually in more detail than I really want.
If you are like me and can't have instructor there all the time, get a decent camera with video capability and get to work. That camera will be worth every penny five times over.