Tutorial question

Hi,

I’m having some difficulty understanding the “preloader and transition for dynamic files” tutorial. What I am trying to do is load an external swf file into the main movie while having a loading animation display within the main movie during the external swf load.

The tutorial I am referring to looks quite easy to learn but what I don’t understand is this code :

onClipEvent (enterFrame) {
if (!loaded && this._url != _root._url) {
if (this.getBytesLoaded() == this.getBytesTotal()) {
loaded = true;
_root.transition.gotoAndPlay(“opening”);
}
}
}

How does that action know to call the profile.swf file?