Possible to load large files behind the scene?

Ok then there's something I'm completely missing out with this code:

var BTS:Number = 0;

var board:Sprite=new Sprite();

this.addChild(board);

board.x=175;

board.y=stage.stageHeight/2.8-board.height/2;

board.buttonMode = true;

var loader:Loader;

var infoBox:TextField;

var image:Bitmap;

var imageData:BitmapData;

var glass:Sprite=new Sprite();

var glassWidth:int=500;

var glassHeight:int=500;

var doDrag:Boolean=false;

var picWidth:Number;

var picHeight:Number;

var dataWidth:Number;

var dataHeight:Number;

var shrinkFactor:Number=.3;

var magFactor:Number=1/shrinkFactor;

function descriptionFill(e:Event):void {

     if (description_mc.width < 588.15) {

          description_mc.width += 45;

     }

     if (description_mc.width >= 588.15 && description_mc.height < 200) {

          description_mc.height += 50;

          description_mc.y += 50;

     }

     if (description_mc.width >= 588.15 && description_mc.height >= 200) {

          stage.removeEventListener(Event.ENTER_FRAME,descriptionFill);

          timer.removeEventListener("timer",timerHandler);

          setChildIndex(descripTag_txt,numChildren-1);

          TweenLite.to(smallImg_mc,2,{alpha:1});

          fullTimer.start();

          mvm_design.alpha = 1;

          descripTag_txt.alpha = 1;

               if (navPanel.x == 0) {

               setChildIndex(smallImg_mc,1);

          }

          setUpLoadBox();

          startApp();

     }

}

smallImg_mc.addEventListener(MouseEvent.CLICK,goFull);

function goFull(e:MouseEvent):void {

     BTS = 1;

     smallImg_mc.removeEventListener(MouseEvent.CLICK,goFull);

     fullMode_txt.visible = false;

     smallImg_mc.visible = false;

}

function startApp():void {

     loader=new Loader();

     loader.load(new URLRequest("resized Images/Zombie Scan Half.jpg"));

     if (BTS == 1) {

          infoBox.text="Loading";

          preload_mc.visible = true;

          loader.contentLoaderInfo.addEventListener(Event.COMPLETE,initPic);

          loader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS,updateInfo);

     }

}

function updateInfo(e:ProgressEvent):void {

     var loaded:Number = e.bytesLoaded;

     var total:Number = e.bytesTotal;

     var pct:Number = loaded/total;

     preload_mc.loader_mc.scaleX = pct;

     infoBox.text="Loading: " + (Math.round(pct*100)) + "%";

}

function initPic(e:Event):void {

     image=Bitmap(loader.content);

     imageData=image.bitmapData;

     dataWidth=image.width;

     dataHeight=image.height;

     image.scaleX=shrinkFactor;

     image.scaleY=shrinkFactor;

     picWidth=image.width;

     picHeight=image.height;

     removeChild(preload_mc);

     board.addChild(image);

     loader.contentLoaderInfo.removeEventListener(Event.COMPLETE,initPic);

     loader.contentLoaderInfo.removeEventListener(ProgressEvent.PROGRESS,updateInfo);

     loader=null;

     infoBox.text="";

     infoBox.visible=false;

     board.addChild(glass);

     glass.filters=[ new DropShadowFilter() ];

     board.filters=[ new DropShadowFilter() ];

     setUpListeners();

}

Code's real long so I just posted what I thought would be necessary to show my problem