El tag <object> es especial para IE, el tag <embed> es reconocido por firefox, por eso no podias verlo en tal navegador, prueba esto:
Código:
<object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,0,0" id="tx_slideshow_pi1" width="465" height="165" align="middle">
<param name="loop" value="false" />
<param name="menu" value="true" />
<param name="quality" value="best" />
<param name="scale" value="noscale" />
<param name="bgcolor" value="fafafa" />
<param name="swliveconnect" value="false" />
<param name="FlashVars" value="file=index.php%3Fid%3D6%26type%3D9005%26slideshow%3D1%26random%3D0%26transition%3Dblocks%26timer%3D5%26navigation%3D1" />
<param name="movie" value="typo3conf/ext/slideshow/pi1/jpgrotator.swf" />
<embed src="typo3conf/ext/slideshow/pi1/jpgrotator.swf" width="465" height="165">
</embed>
</object>