[wvxvw]

var _txt:TextField = _root.createTextField("_txt", 0, 5, 5, 300, 200);
with(_txt){
	autoSize = true;
	type = "dynamic";
	html = true;
	border = true;
	wordWrap = true;
	borderColour = 0x000000;
	multiline = true;
	htmlText = "<img src='screen_01.jpg' id='image1'>";
}
_root.onEnterFrame = function(){
	trace(_txt.image1.getBytesLoaded());
}

Проверил, работает