Rien ne vaut un bon exemple, alors en voici un :

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" 
applicationComplete="AppComplete()" initialize="Init()" 
height="300" width="350" layout="absolute">
    
<mx:Script>
  <![CDATA[
    import mx.utils.URLUtil;
    import flash.system.Capabilities;
 
	private var time:Number;
	
	private function Init():void {
		time = getTimer();
	}
 
    private function AppComplete():void {
            	
	 Infos.htmlText = "<B>Server</B><BR>url: "
	 + URLUtil.getServerNameWithPort(Application.application.loaderInfo.url)
         + "<BR>Protocol: "
         + URLUtil.getProtocol(Application.application.loaderInfo.url);
               
         Infos.htmlText += "<BR><BR><B>Application</B><BR>Loading time: "
         +(getTimer() - time).toString()+"ms"
         + "<BR>FrameRate: " + Application.application.loaderInfo.frameRate
         + "<BR>ASVersion: " 
         + Application.application.loaderInfo.actionScriptVersion
         + "<BR>BytesTotal: " 
         + Math.round(Application.application.loaderInfo.bytesTotal/1024)+"KB"; 
                
         Infos.htmlText += "<BR><BR><B>User infos</B><BR>Flash Player version: " 
         + Capabilities.version
         + "<BR>Player has debug capability: " 
         + (Capabilities.isDebugger ? "yes":"no")
         + "<BR>Operating system: " + Capabilities.os
         + "<BR>Screen Resolution: " 
         + Capabilities.screenResolutionX +"x" + Capabilities.screenResolutionY
         + "<BR>Language: " + Capabilities.language;
  
         }      
  ]]>
</mx:Script>
<mx:TextArea id="Infos" left="25" top="25" right="25" bottom="25"/>
</mx:Application>

Ce qui nous donne :

;

Attention : Pour avoir accès à Application.application il faut utiliser l'event ApplicationComplete et non CreationComplete.

Voilà, ça peut toujours servir 8-) .