这段代码是什么意思啊？？

loadMovie("logo.png", lo);
xmin = 80;
xmax = 900;
ymin = 50;
ymax = 320;
eanum = 20;
i = 1;
while (i <= eanum) {
sm.duplicateMovieClip(("m" + i), i);
this[("m" + i)].ang = 0;
this[("m" + i)].speed = 3;
this[("m" + i)].onEnterFrame = function() {
this.dx = Math.cos(this.ang) * this.speed;
this.dy = Math.sin(this.ang) * this.speed;
this._x += this.dx;
this._y += this.dy;
this.ang += (Math.random() - 0.5);
this._rotation = this.ang * 1.5915494309189535;
if (this._x < (xmin - this._width / 2)) {
this._x = xmin - this._width / 2;
}
if (this._x > (xmax - this._width / 2)) {
this._x = xmax - this._width / 2;
}
if (this._y < (ymin - this._height / 2)) {
this._y = ymin - this._height / 2;
}
if (this._y > (ymax - this._height / 2)) {
this._y = ymax - this._height / 2;
}
updateAfterEvent();
};
i++;
}
_root.onEnterFrame = function() {
this[("m" + Math.ceil(Math.random() * _root.eanum * 8))].play();
};
myPath = "www.webchina.com.cn";
checkPath = _url;
if (checkPath.indexOf(myPath) == -1) {
unloadMovieNum(0);
}
请各位高手详细解释给小的听，急用啊，谢谢！！
这个flash导出来显示不了呢，只有张背景图．想知道是怎么回事，是否是源码写错了，还是问题出现在哪！！
各位flash高手们帮帮忙吧，谢谢了！！