Hola Cerberus8 Con este código tu flash queda centrado para cualquier resolución tanto a lo ancho como a lo alto, pruebalo:
Saludos
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<table width="100%" height="100%" border="0" cellpadding="0" cellspacing="0">
<tr>
<td aling="center" valign="middle">
<table width="755" border="0" valign="middle" align="center" cellspacing="2" cellpadding="2">
<tr>
<td>
<object classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" codebase="http://fpdownload.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,0,0" width="755" height="440" id="principal_futuro" align="middle">
<param name="allowScriptAccess" value="sameDomain" />
<param name="movie" value="principal_futuro.swf" />
<param name="quality" value="high" />
<param name="bgcolor" value="#1f3c76" />
<embed src="principal_futuro.swf" quality="high" bgcolor="#1f3c76" width="755" height="440" name="principal_futuro" align="middle" allowscriptaccess="sameDomain" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" />
</object>
</td>
</tr>
</table>
</td>
</tr>
</table>