Код:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1251" />
<title>Untitled Document</title>
<script type="text/javascript">
function runActive(width, height, play, bgcolor){
var curmov = Math.round(Math.random()*2);
movies = new Array('mov1', 'mov2', 'mov3'); //названия свфок
filename = movies[curmov];
document.write("<object classid=\"clsid:d27cdb6e-ae6d-11cf-96b8-444553540000\" codebase=\"http://fpdownload.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=8,0,0,0\" width=\""+width+"\" height=\""+height+"\" id=\""+filename+"\" align=\"top\">");
document.write("<param name=\"allowScriptAccess\" value=\"sameDomain\" >");
document.write("<param name=\"movie\" value=\""+filename+".swf\" >");
document.write("<param name=\"play\" value=\""+play+"\" >");
document.write("<param name=\"menu\" value=\"false\" >");
document.write("<param name=\"quality\" value=\"high\" >");
document.write("<param name=\"scale\" value=\"showall\" >");
document.write("<param name=\"bgcolor\" value=\""+bgcolor+"\" >");
document.write("<embed src=\""+filename+".swf\" play=\""+play+"\" menu=\"false\" quality=\"high\" scale=\"showall\" bgcolor=\""+bgcolor+"\" width=\""+width+"\" height=\""+height+"\" name=\""+filename+"\" align=\"top\" allowScriptAccess=\"sameDomain\" type=\"application/x-shockwave-flash\" pluginspage=\"http://www.macromedia.com/go/getflashplayer\" ></object>");
}
</script>
</head>
<body>
<script type="text/javascript">runActive('100px', '100px', 'true', '#ffffff')</script>
</body >
</html>
типа того. жаваскрипт в отдельный файл тока вынеси.