video tag DOM events problem

video tag DOM events problem

i am trying to use the DOM events for the video tag (html5 video)
i am using the events listed here
http://www.w3schools.com/tags/ref_av_dom.asp

yet no matter which event i use the code runs when i load the page not when the event is triggered

this is my code
 
<script>
document.getElementById('vidz').volumechange() = hollow();
function hollow(){
 alert("test");
}
</script>


 
no matter which event i use in place of volumechange() i get the same problem
i have also tried using volumechange() without the brackets but it does not make any difference.