Using jQuery to update the st_url attribute of the sharethis chicklet button?

Question

I am dynamically updating the attribute 'st_url' of all of the sharethis spans to the url of a video clicked with jQuery. In firebug you can see it is updating the st_url attribute of my spans, however I the sharethis button is still tied to the initial url. I read I may have to reinit the elements, but I am unsure of the best way to do this? Has anyone done this or have any idea of the best way to re-initialize the buttons with the updated url? Thanks!

Sharethis includes and init:

<script type="text/javascript">
    var switchTo5x=true;
</script>
<script type="text/javascript" src="http://w.sharethis.com/button/buttons.js"></script>
<script type="text/javascript">
    stLight.options({publisher:'xxxx'});
</script>

My markup:

<span st_url="http://sharethis.com" class='st_stumbleupon' ></span>
<span st_url="example" class='st_facebook' ></span>
<span st_url="example" class='st_twitter' ></span>
<span st_url="example" class='st_email' ></span>

My jQuery to update the attr="st_url" when a user clicks on a video:

//note: this is triggered by .bind('click')
var youtubeID = $(this).attr('id');
$('#container div > span').each(function(){
    //update sharethis to current video
    $(this).attr('st_url','http://www.youtube.com/watch?v=' + youtubeID);
});