Make that Object Video Dissapear!

im using a mootools popup box to play a youtube video

its using javascript to control the "close" button.. and the close button uses this function

clickClose: function(){
$(this.box).effect('opacity',{ wait:true, duration:this.fadeSpeed, transition:Fx.Transitions.linear }).chain(function(){
}).start(this.opacity,0); this.box.setStyle('display','none');
this.isVisible = false;
},

seeing as ow i have a playing video in the box...that simply wasnt enough..because the video would continue playing after the box is closed... (you would ehar audio)

so i modified the code by adding

this.box.setStyle('display','none');

this did the TRICK!!! ....in firefox.....sadly Internet Explorer is refusing to destroy that video upon click....

are there any ideas as to how i can destroy that video across all browsers when that button is clicked....i say "destroy" because im mad! lol

but i simply want the video to dissapear...off the screen and off the site with no mysterious audio afterwards.