Ejemplo de creacion de control personalizado para permitir contenido flash (SWF) en paginas ASPX
<!-- REGISTRAMOS CONTROL -->
<%@ Register Assembly="Flash" Namespace="Flash" TagPrefix="cc1" %>
<!-- AGREGAMOS CONTROL A PAGINA -->
<cc1:FlashControl ID="FlashControl1" runat="server"
BackColor="#000"
Quality="high"
Movie="filename.swf"
Height="180px"
Width="389px"
Align="middle" />
<!-- MUESTRA DEL RESULTADO FINAL EN CLIENTE (RENDERIZACION) -->
<object id="ctl00_ContentPlaceHolder1_FlashControl1" classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" codebase="http://fpdownload.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=8,0,0,0" quality="high" movie="filename.swf" align="middle" style="background-color:#000000;height:180px;width:389px;">
<param name="bgcolor" value="#000000"/>
<param name="movie" value="images/940.swf"/>
<param name="quality" value="high"/>
<embed src="filename.swf" mce_src="filename.swf" quality="high" bgcolor="#000000" width="389px" height="180px" align="middle" allowScriptAccess="sameDomain" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer"</embed>
</object>