Randomly Displaying Movie Clips

Hi all,
I would like to know how to randomly display movie clips on my website . After doing some research I’ve found the following scripts that’s supposed to do that:

filename = [“circular.swf”, “vibration.swf”, “random_movement.swf”];
path = “http://www.kirupa.com/developer/actionscript/animation/”;
i = filename.length;
k = Math.floor(Math.random()*i);
loadMovie(path+filename[k], movieTarget);

I have just two questions regarding the script above;

  1. What is movieTarget, is it a built in variable or is it a user defined variable?
  2. Can the script above play movie clips that are on different layers and if not how can I do that?

Thank you in advance for your response.