HTML and getting live updated numbers

I use WebRequest-->WebResponse-->StreamReader to get HTML for certain sites and then extract the data.  But when I get to certain data that updates live (say every five minutes), I'm not sure how to access that information because it's not found in the HTML.  In most cases, reading the HTML is working for me, but with live data do I have to totally change my tactics for getting the info?

If an example would help, I'm trying to get data off the site http://www.ise.ie/

Right in the middle of the page is an updating number for "ISEQ® OVERALL" with a number around 5,000.  This number is not in the HTML and as far as I can tell is showing up somewhere in these lines of HTML:

        <div id="iseq-overall" class="iseq-overall" style="display:none;">
            <p>&#160;</p>
            <p>&#160;</p>
        </div>
        <div id="iseq-loader" class="iseq-overall home-loader" style="height:54px">
            <img alt="iseq-loading" src="/images/various/iseq-loader.gif" />
        </div>
        <div class="cell">

Any help in understanding this would be greatly appreciated, even links to more information, because I haven't been able to put together a good search to lead me in the right direction.

Thanks.