Do you use
<embed src="one.dcr" width=640 height=480><br>
<embed src="two.dcr" width=640 height=480><br>
If yes, it could be done similar to prelodaing images.
There is a collection embeds, which you could use.
<HTML>
<HEAD>
<TITLE> DCR </TITLE>
<script language="JavaScript">
function emb(){
em = document.embeds;
em[0].src = 'one.dcr';
em[1].src = 'two.dcr';
document.all.dcrOneDiv.innerHTML = "<embed src='waterpolo.dcr' width=640 height=480>"
document.all.dcrTwoDiv.innerHTML = "<EMBED SRC='hacker.dcr' width=512 height=342>"
}
</script>
</HEAD>
<BODY onLoad="emb();">
<!-- some hidden embeds without sources - in order to have embed collection -->
<embed width="0" height="0"><embed width="0" height="0">
<div id="dcrOneDiv" name="dcrOneDiv">Loading One... Please wait.</div>
<div id="dcrTwoDiv" name="dcrTwoDiv">Loading Two... Please wait.</div>
</BODY>
</HTML>