Hover Caption

1

I’m using this hover caption on my site:
http://www.kirupa.com/developer/mx/captions.htm

But I would like to have the hover caption appear for only a short amount of time (2 seconds?). Any tips to do this? Cause I don’t know where to start/search (:

Here’s the main part of the code:

onClipEvent (enterFrame) {
    if (_root.x==1) {
        this._alpha = 50;
    } else {
        this._alpha = 0;
    }
}

Thanks!