How thay make it sound like that?

http://www.youtube.com/watch?v=2CVfsSb49sM

from min 3:04 to the end of the track the line of the melody pumping by a Side-chain??? Or that form of musical instruments including spacious??? all the Euphoric trance Genre is like that (armada music or alex m.o.r.p.h or )
I want to know how to do it and I can not get The same result in my productions.

thanks Daniel tzariker

It could be sidechaining but it sounds more like of beat notes being played with a sidechained pad behind it playing chords with a similair trancy pad sound.