Tendrias que agregar lo que esta en negrita a tu html:
Código:
<object width="100%" height="100%" classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=7,0,19,0" >
<param name="movie" value="prueba.swf" />
<param name="quality" value="high" />
<PARAM NAME=scale VALUE=noscale>
<PARAM NAME=salign VALUE=LT>
<embed src="prueba.swf" scale=noscale salign=LT WIDTH="100%" HEIGHT="100%" quality="high" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" ></embed>
</object>