Displaying filename of a dynamic picture

I have constructed the photo gallery using the tutorial from this site. But I would like to add a dynamic text box that displays a caption (or at least the filename) for each photo when it appears. The code looks like this:

[font=Arial]this.pathToPics = “”;
this.pArray = [“1.jpg”, “2.jpg”, “3.jpg”, “4.jpg”];
this.fadeSpeed = 20;
this.pIndex = 0;
// MovieClip methods ----------------------------------
// d=direction; should 1 or -1 but can be any number
//loads an image automatically when you run animation
loadMovie(this.pathToPics+this.pArray[0], _root.photo);
MovieClip.prototype.changePhoto = function(d) {
// make sure pIndex falls within pArray.length
this.pIndex = (this.pIndex+d)%this.pArray.length;
if (this.pIndex<0) {
this.pIndex += this.pArray.length;
}
this.onEnterFrame = fadeOut;
};
MovieClip.prototype.fadeOut = function() {
if (this.photo._alpha>this.fadeSpeed) {
this.photo._alpha -= this.fadeSpeed;
} else {
this.loadPhoto();
}
};
MovieClip.prototype.loadPhoto = function() {
// specify the movieclip to load images into
var p = _root.photo;
//------------------------------------------
p._alpha = 0;
p.loadMovie(this.pathToPics+this.pArray[this.pIndex]);
this.onEnterFrame = loadMeter;
};
MovieClip.prototype.loadMeter = function() {
var i, l, t;
l = this.photo.getBytesLoaded();
t = this.photo.getBytesTotal();
if (t>0 && t == l) {
this.onEnterFrame = fadeIn;
} else {
trace(l/t);
}
};
MovieClip.prototype.fadeIn = function() {
if (this.photo._alpha<100-this.fadeSpeed) {
this.photo._alpha += this.fadeSpeed;
} else {
this.photo._alpha = 100;
this.onEnterFrame = null;
}
};
// Actions -----------------------------------------
// these aren’t necessary, just an example implementation
this.onKeyDown = function() {
if (Key.getCode() == Key.LEFT) {
this.changePhoto(-1)
} else if (Key.getCode() == Key.RIGHT) {
this.changePhoto(1)
}
};
Key.addListener(this);[/font]

Any help would be greatly appreciated.