Well, I am sure they aren't going to give out all their secret recipes, but one little hint they will let you in on is the light beam effect that they use through-out their site. Mark Fennell, of Flashkit, and the creator of the effect you see, Yasuto Suga, are the writers of the famed tutorial. There are many steps in the lesson, which is a good idea. The tutorial is not all that easy, so patience should be a consideration. There are 8 steps involved with this lesson where many factors play a role.
Angles are very important as well as the tweens.
Yet, viewing a Flash movie with out the music can give the overall effect a whole new persona. It may seem peculiar, but let me explain. For example, pick any Flash site that you know has an introduction with music. First, watch the Flash intro with the volume turned up, then turn your volume down and then watch the intro again. Music a lot of times enhances the senses, but there can be beauty in a Flash site that holds your eyes in a way that makes you forget about even listening.