I have been through periods where I have taken note and those where I have not. At the moment it is the later of these, but at some point this may change again.
The advantages of note taking or video taping are as follows.
1. They provide a stimilus for remembering the techniques or drills covered in the course and the feeling of carrying them out.
2. You can force yourself through the experiential learning cycle by writing notes after the class. By this I mean that those of us who do not ponder the why and wherefore of the material we have been shown are forced to do so.
3. Video is great because it captures the event as it happened and not how you imagined it to happen.
I am sure there are other advantages, but here are some of the disadvantages.
1. You spend all your time behind the camera and not training.
2. You write down things wrong in your notes because at the time you did not understand them or you remembered them incorrectly when you got time for note taking.
3. Your notes become something that you cannot deviate from.
4. You become a collector of footage or notes and the application of the art becomes less important that obtaining the next piece of information or footage. This is definately something that plagues the Bujinkan martial arts.
I have found that if using notes as part of my training it is as important to write about how I felt during the class and my performance, as it is to document the drills or techniques.
Paul Genge
http://www.russianmartialart.org.uk