What exactly is it? I have read the informaton on the miyazawa.com site but i dont really understand it. Does anyone know anything about it?

http://www.flute4u.com/brannen.html

The Brogger Flute: Our most well known, popular instrument, this flute combines the traditional fingerings of the Boehm system with the enormous advantages of the Brögger Mekanik™. This mechanism increases the reliability of the keywork and reduces internal friction, allowing keys to be adjusted much more closely to individual preferences. A soldered tonehole flute, the Brögger offers the widest possible range of options, including choice of materials and custom keywork.

Here`s the patent for the Brogger design:

http://www.flutist.dk/images/Broegger%20Mek.%20US.jpg

A far more descriptive site on the Brogger mechanism:
http://www.flutist.dk/english.htm

Can someone explain how it is different to the normal flute system? What are the advantages?

The advantage to the Brogger system is that it can provide a faster, more responsive mechanism. It also goes out of adjustment slower than most flutes. I would suggest trying it out before you decide to buy it, because i`ve heard not everyone likes the feel of it and it can be hard to adjust.