This has really helped me quite a bit to become a better drummer.
I'm sure that more seasoned players don't necessarily need this but if you are new to playing or trying to improve your game, do this if you can.
It's pretty educational watching your style, tempo and body movement or lack of. I was struck with the amount of over-crashing of cymbals that I do! Nobody ever mentioned this to me.
Another thing I noticed, play with a lot of body movement. Sitting there like a lump straight up can really mess up your playing. I'm teaching myself to apply more "body English" to my playing. It has helped tremendously. Ay least I think it has.