我将如何提取直接视频URL从视频嵌入代码在c#

我在一个类似Youtube的视频托管网站上为其中一个视频生成了一些视频嵌入代码。我需要提取到视频源(*.m4v)的直接链接。在下面的示例中，我想提取值"http://play.op.ac.nz/images/media/beb431bc59587dc71e10939d214e9515_1315897772。m4v"并将其放入字符串:

<script type="text/javascript" src="http://play.op.ac.nz/js/embed.js.php?key=beb431bc59587dc71e10939d214e9515"></script>
<noscript>
  <!-- Version SVN: $Id: _playerVideo.php 19008 2011-05-17 19:06:32Z sven $ -->
  <div id="flash">
    <div id="flashcontent">
      <object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" id="flvplayer_4e71fa175218d" name="c6a80378-3eb2-47e7-8415-ba1f7cff037e" width="720" height="406" style="position:relative;top:0;left:0;z-index:9999;">
        <param name="movie" value="http://play.op.ac.nz/flash/vimp.swf" />
        <param name="flashvars" value="hosturl=http%3A%2F%2Fplay.op.ac.nz%2Fmedia%2Fflashcomm&amp;mediaid=195&amp;context=embeded&amp;skin=http%3A%2F%2Fplay.op.ac.nz%2Fflash%2Fskins%2Fice_white.swf&amp;autohidesidebaronplay=true" />
        <param name="scale" value="true" />
        <param name="allowfullscreen" value="true" />
        <param name="allowscriptaccess" value="always" />
        <param name="wmode" value="opaque" />
        <!--[if !IE]>-->
        <object type="application/x-shockwave-flash" data="http://play.op.ac.nz/flash/vimp.swf" width="720" height="406" wmode="opaque">
          <param name="flashvars" value="hosturl=http%3A%2F%2Fplay.op.ac.nz%2Fmedia%2Fflashcomm&amp;mediaid=195&amp;context=embeded&amp;skin=http%3A%2F%2Fplay.op.ac.nz%2Fflash%2Fskins%2Fice_white.swf&amp;autohidesidebaronplay=true" />
          <param name="scale" value="true" />
          <param name="allowfullscreen" value="true" />
          <param name="allowscriptaccess" value="always" />
          <param name="wmode" value="opaque" />
          <!--<![endif]-->
          <div class="leanback-player-video">
            <video id="index_video" width="720" height="406" preload="metadata" controls="" poster="http://play.op.ac.nz/cache/99590fa59570e38b09e63000c99a6859.jpg">
              <source src="http://play.op.ac.nz/images/media/beb431bc59587dc71e10939d214e9515_1315897772.m4v" type="video/mp4" />
              <source src="http://play.op.ac.nz/images/media/beb431bc59587dc71e10939d214e9515_1315897772.webm" type="video/webm" />
              <source src="http://play.op.ac.nz/images/media/beb431bc59587dc71e10939d214e9515_1315897772.ogv" type="video/ogg" />
              <p style="margin: 15px;">
                Hint: Unfortunately your browser does not have Flash Player installed or the Flash Player version is outdated. You need Flash Player to view media in this community. <a href="http://www.macromedia.com/go/getflashplayer">Download Flash Player</a>
              </p>
              <img alt="How to safely operate a power actuated nail gun" title="How to safely operate a power actuated nail gun" src="http://play.op.ac.nz/cache/99590fa59570e38b09e63000c99a6859.jpg" />
            </video>
          </div>
          <!--[if !IE]>-->
        </object>
        <!--<![endif]-->
      </object>
    </div>
  </div>
</noscript>

我已经做了一个搜索，并找到了大量的解决方案在PHP和Python，但没有什么我可以破译。我有一段时间没有接触c#了，所以任何帮助都会很感激。