Ну, можно так..

Код:
import flash.display.BitmapData;
MovieClip.prototype.bitmapCopy = function(n:String, d:Number):MovieClip {
var clip:MovieClip = this._parent.createEmptyMovieClip(n, d);
var bmp:BitmapData = new BitmapData(this._width, this._height);
bmp.draw(this);
clip.attachBitmap(bmp,0);
return clip;
};
//----------------------------------------------------
var mcLoader:MovieClipLoader = new MovieClipLoader();
var obj:Object = {};
mcLoader.addListener(obj);
mcLoader.loadClip("test.gif",mc);
obj.onLoadInit = function(mc:MovieClip) {
mc.bitmapCopy("mc2",1);
};