I think there are 2 very important keys to getting good (and all of the DVDs and instructional vids in the world can't take you to the top of your game IMO):
1. Observation is key: I spent many years going to national shows as a youth just to watch other fit, groom, and clip. It takes a lot of time and for goodness sakes if you really are lost on a specific technique or style just ask the question because most folks are more than willing to share their knowledge.
AND
2. DO IT! No video is going to train your hands to sense when a calf is getting ready to shift on its feet. I would suggest using older show heifers or young calves (only to minimize any "damage" to your show stock) however, I do realize this is sometimes a luxury. I have goofed some calves up pretty bad in my day, bu it is important to remember that the hair grows back.
I know these things have already been said but thought you might like a different perspective. GOOD LUCK!