Включите в рассчет загружаемые клипы.

Код AS1/AS2:
var loadingPool: Object = new Object();
var mcLoader: MovieClipLoader = new MovieClipLoader();
mcLoader.loadClip("clip1.swf", mcPortfolio);
this.loadingPool[mcPortfolio._name] = mcPortfolio;
mcLoader.loadClip("clip2.swf", mcAbout);
this.loadingPool[mcAbout._name] = mcAbout;
function getBytes(funcName:String):Number {
var result: Number = 0;
var mc: MovieClip;
var bytes: Number;
for (var i:String in this.loadingPool) {
mc = this.loadingPool[i];
bytes = mc[funcName].call(mc);
if (bytes) result += bytes;
}
result += this[funcName].call(this);
return result;
}
function onEnterFrame():Void {
var nLoading:Number = this.getBytes('getBytesLoaded') / this.getBytes('getBytesTotal');
}