The magic lantern DVDs are excellent IMO, although I don't recall them ever making a DVD or a book for that matter on any type of flash. As Jenny recommended, the Blue Crane Digital DVD for flash would work, although remember that there are alternatives. I think that instead of learning what your SB-600 can do, you should learn how to work with flash in general. For example, you wouldn't buy a Nikon D3000 DVD hoping to learn what shutter speed or aperture is, you would buy it to learn how to control the shutter speed or aperture.
Personally, I don't know much about flash. I know some basic techniques, such as using a bounce flash (Bouncing your flash off a roof or a wall to get a less harsh look if you weren't already aware of that) by tilting the head, although I'm not any expert on the manual controls of flash, I really could only operate a Nikon SB-400 without any problems!
I found an interesting website here
explaining flash, and how to do some manual work.
Hope that I helped!