Try doing something like this:

<div class="par" id="inspiration{$idNum}"></div>
<script type="text/javascript">
var flashvars = {file: '<xsl:value-of select="$file"/>',image: '<xsl:value-of select="$fileImage"/>',frontcolor: 'ffffff',lightcolor: 'cc9900',skin: '/swf/overlay.swf',controlbar:'none'};

var params = {menu: 'false',allowfullscreen:'false',allowscriptaccess:'always',wmode:'opaque',bgcolor:'#002c39'};
var attributes = {};

swfobject.embedSWF('/swf/player.swf', 'inspiration<xsl:value-of select="$idNum" />', '290', '177', '9.0.0','/swf/expressInstall.swf', flashvars, params, attributes);
</script>

I get an xslt error on <xsl:valueof at flashvars:

<script type="text/javascript">
var flashvars = {file: '<xsl:value-of select="$showme"/>',image:'http://web.u0810495.fsdata.se/images/preview',frontcolor: 'ffffff',lightcolor: 'cc9900',controlbar:'none'};

var params = {menu: 'false',allowfullscreen:'false',allowscriptaccess:'always',wmode:'opaque',bgcolor:'#002c39'};
var attributes = {};

swfobject.embedSWF('/endforward umbraco flv/jwplayer/player.swf', 'mttVid<xsl:value-of select="$vidToPlay/node/@id"/>', '180', '140', '9.0.0','ply', flashvars, params, attributes);
</script>

When I look at my source this is what gets rendered:

 <div id="myVideo1102"><a href="http://www.macromedia.com/go/getflashplayer">För att se filmen behöver du en flashspelare. Hämta den här.</a></div><script type="text/javascript">
    var flashvars = {file: '/media/995/gyrid_tone2.flv',image: '/images/preview.jpg',frontcolor: 'ffffff',lightcolor: 'cc9900',controlbar:'none'};
 
 
    var mttVid1102 = new SWFObject("/endforward umbraco flv/jwplayer/player.swf","ply","180","140","9",flashvars);
    mttVid1102.addParam("allowfullscreen","true");
    mttVid1102.addParam("allowscriptaccess","always");
     
    mttVid1102.write("myVideo1102");
  </script>

 Im no javascripter so for mer its not obvióus what is wrong. Anyone?

Solved it finally:

<xsl:template match="/">
  <xsl:value-of select="videoNode"/>
  <xsl:variable name="showMe" select="umbraco.library:GetMedia($vidToPlay/node/@id, 0)/data [@alias = 'umbracoFile']" />
<div id ="myVideo{$vidToPlay/node/@id}">
    <a href="http://www.macromedia.com/go/getflashplayer">För att se filmen behöver du en flashspelare. Hämta den här.</a>  </div>
  
 <script type="text/javascript">
    var mttVid<xsl:value-of select="$vidToPlay/node/@id"/> = new SWFObject("/endforward umbraco flv/jwplayer/player.swf","ply","180","140","9","#000000");
    mttVid<xsl:value-of select="$vidToPlay/node/@id"/>.addParam("allowfullscreen","true");
    mttVid<xsl:value-of select="$vidToPlay/node/@id"/>.addVariable("allowscriptaccess","always");
    mttVid<xsl:value-of select="$vidToPlay/node/@id"/>.addVariable('file','<xsl:value-of select='$showMe'/>');
    mttVid<xsl:value-of select="$vidToPlay/node/@id"/>.addVariable('image','preview.jpg');
    mttVid<xsl:value-of select="$vidToPlay/node/@id"/>.write("myVideo<xsl:value-of select="$vidToPlay/node/@id"/>");
  </script>

</xsl:template>

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