// create the target clip you'll be loading into...
var holder:MovieClip = this.createEmptyMovieClip("holder", this.getNextHighesteDepth());
// this is the base name for your movies...
var preFix:String = "movie_";
// this is the total number of swf's in your folder... i used 20 for this example
var total:Number = 20;
/*
NOTE: if you put the images in a separate folder you
should specify the path in the preFix variable
ex. var preFix:String = "foldername/movie_";
*/
// this loads a swf by taking the base name, appending a random # from 0-'total'
// then appending the .swf extension on the end.. completing the file name
holder.loadMovie(preFix + random(total) + ".swf");
stop();