<div id="mycontent" style="width:100px;height:100px;position:absolute;left:0px;top:0px;z-index:2;">
Lorem ipsum dolor sit amet
</div>
 
<div id="mybg" style="position:absolute;left:0px;top:0px;z-index:1;">
  <object width="100" height="100">
    <param name="movie" value="some.swf" />
    <embed width="100" height="100" src="some.swf" type="application/x-shockwave-flash" />
  </object>
</div>