this["container"].attachMovie("useLoad", "useLoadMc", this.getNextHighestDepth());
attachMovie 不等于直接赋值，而是将库链接"useLoad"影片命名为"useLoadMc"，并添加到this["container"]容器中；
所以 remove(this["container"]["useLoadMc"])，仅仅删除被添加到容器this["container"]的useLoadMc影片剪辑
/**
* 删除非自身的影片
* @param _mc
*/
public function removeAllIn(_mc:Object):Void
{
var m:MovieClip;
for (var i in _mc)
{
m = _mc[i];
if ((m != _mc))
{
remove(m);
}
}
}
/**
* 删除自身影片
* @param _mc
*/
public function remove(_mc:MovieClip):Void
{
_mc.getDepth() < 0 ? _mc.swapDepths(_mc._parent.getNextHighestDepth()):0;
_mc.removeMovieClip();
_mc.unloadMovie();
_mc = null;
}
原文：https://www.cnblogs.com/dt1991/p/10281461.html