help with pulling and using uri from rss

I am relatively new to XSL transforms so I apologize if my language or verbage is incorrect.

I am trying to invoke a JS function of a flash player which requires a URI. In order to do this I would like to take the RSS feed, the snippet below, and grab the uri from the <enclosure> tag. You will see that there is a &uri=channels/39174/186941 inside of the url="" i would like to grab this piece and insert it into my XSL <a href= as currently defined by $item_enclosure.

Here is my XML:

<item>
<title>New Show: Mobile Show 434</title>
<link>http://www.kyte.tv/ch/39174-flocam/186941-mobile-show-434</link>
<guid>http://www.kyte.tv/ch/39174-flocam/186941-mobile-show-434</guid>
<description>&lt;a href='http://www.kyte.tv/ch/39174-flocam/186941-mobile-show-434'&gt;&lt;img src='http://media06.kyte.tv/store/005/06/crr/0808/05/04/694822-37003-08042008077_120_90-tom-1000.jpg?aid=21808&amp;h=c572dfe49ef7e0704a003559429b4605' title='Mobile Show 434' width='120' height='90' alt='Mobile Show 434' border='0'/&gt;&lt;/a&gt;&lt;br&gt;produced by coflo.</description>

<pubDate>Tue, 05 Aug 2008 04:10:00 +0000</pubDate>
<media:content url="http://www.kyte.tv/flash.swf?appKey=MarbachViewerEmbedded&amp;uri=channels/39174/186941&amp;layoutMode=default" fileSize="30" type="application/x-shockwave-flash" height="425" width="425" duration="1"/>
<enclosure url="http://www.kyte.tv/flash.swf?appKey=MarbachViewerEmbedded&amp;uri=channels/39174/186941&amp;layoutMode=default" length="30" type="application/x-shockwave-flash"/>
</item>

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As you can see in my XSL im able to pull the url and insert it but i have no idea how to extract the uri=channels/39174/186941

Here is my attempt XSL:

<xsl:template match="item">
<xsl:variable name="item_link" select="link"/>
<xsl:variable name="item_enclosure" select="enclosure/@url"/>
<xsl:variable name="item_title" select="description"/>
<xsl:variable name="item_media" select="media"/>
<div class="subHead" style="width:300px;">
<a href="javascript:void(kyteplayer.setURI('{$item_enclosure}'))"><xsl:value-of select="title" disable-output-escaping="yes"/></a></div>
<div style="width:300px;">
<xsl:value-of select="description" disable-output-escaping="yes"/><br/></div>

(<xsl:value-of select="pubDate"/>)<br/> <hr/>