I'm sure most of us use swfObject, which in my opinion is the best option when it comes to embedding flash.

Lately I've been having a lot of fun with mootools and needed a way to embed flash dynamically. Basically I wanted my flash file to be embedded after a mootools click event was triggered.

So without further ado..

window.addEvent('domready', function() {
 
//get the div I want to embed my flash into.
var flashcontainer = $('flashcontainer');
 
//set all the flash properties
var file = 'file.swf';
var moviename = 'nameMyFlash';
var width = '640';
var height = '424';
var version = '9';
var bgcolor = '#000000';
 
//create the function that will fuse swfObject with mootools
var embedFlash = function(){
    var so = new SWFObject(file, moviename, width, height, version, bgcolor);
	     so.addParam("quality", "high");
	     so.addParam("align", "middle");
	     so.addParam("play", "true");
	     so.addParam("loop", "true");
	     so.addParam("scale", "exactfit");
             so.addParam("allowFullScreen", "true");
	     so.addVariable("variable1", "variable 1 value goes here");
	     so.addVariable("variable2", "variable 1 value goes here");
	     so.write(flashcontainer);
}
 
//get button by id
var myButton = $('mybutton'); 
 
// create click event to fire my function called "embedFlash()"
myButton.addEvent('click', embedFlash); 
 
});

And that's it.. Hope it helps....

You can download the latest tools used above from the links below:
MooTools - download release 1.2.3 or SWFObject 2.2