I want to refresh the output of the script below. Is this json? Do I need to add a crossdomain policy in my site?

<div id="nowplaying">
   <script src="http://s4.total-streaming.com/xml.php?station=1269&get=js"></script>
</div>

Edit:
This is what I'm trying based on @alexn advise, but still doesn't refresh.

<div id="nowplaying">
    <script id="nowplaying-script" src="http://s4.total-streaming.com/xml.php?station=1269&get=js"></script>

    <script>
        setInterval(function () {
            $('#nowplaying-script').attr('src', 'http://s4.total-streaming.com/xml.php?station=1269&get=js');
        }, 1000);
    </script>
</div>

Note Firebug: Resource interpreted as script but transferred with MIME type text/html. xml.php:-1