Jquery code doesn't work after paging?

i have written below code in my content page which has listview and datapager

    <asp:Content ID="content2" runat="server" ContentPlaceHolderID="HeadContent">
    <link href="../js/fancybox/jquery.fancybox-1.3.4.css" rel="stylesheet" type="text/css" />

    <script src="http://ajax.aspnetcdn.com/ajax/jquery/jquery-1.5.1.js" type="text/javascript"></script>

    <script src='<%=ResolveClientUrl("~/js/fancybox/jquery.fancybox-1.3.4.js")%>' type="text/javascript"></script>

    <script src='<%=ResolveClientUrl("~/js/fancybox/jquery.easing-1.3.pack.js")%>' type="text/javascript"></script>

    <script src='<%=ResolveClientUrl("~/js/fancybox/jquery.mousewheel-3.0.4.pack.js")%>'type="text/javascript"></script>

    <script type="text/javascript"> 
     $(document).ready(function () { 
   $(".fancyYoutube").fancybox({ 
             'transitionIn': 'elastic',
             'transitionOut': 'fade',
             'width': 680,
             'height': 495,
             'type': 'swf'
             }); 
            });
    </script>
</asp:Content>

This works fine.. but when i do paging then code written doesn't work.

I could see that in visual studio one file is created 'Jscript-window script block'. and code written

__doPostBack('ctl00$BodyContent$lvEnglishMovieList$dpgGallery$ctl01$ctl01','')

What does this mean??

Issue solved.

<script type="text/javascript">
    $(document).ready(function () {
        Sys.WebForms.PageRequestManager.getInstance().add_endRequest(showtrailer);
        showtrailer();
    });
    function showtrailer() {
        $(".fancyYoutube").fancybox({
            'transitionIn': 'elastic',
            'transitionOut': 'fade',
            'width': 680,
            'height': 495,
            'type': 'swf'
        });
    }
</script>

My listview was inside the update panel becuase of which i had to write these code. Got help from asp.net forum and the link is HERE