I have played this DVD for about 5-6 times, maybe more, and I believe that this is a very inspirational technique to try on. Maybe it is not supposed to be called Modulation, instead Push-Shadow method since the entire idea of the technique IMHO is to manually draw and push every possible shadow up to surface.
Even at it's infancy stage, I believe the modulation method is very useful to bring a more realistic finish to the model.
Just one comment; I wish that the airbrush chapter be placed under extras or something, but not in the main program.