Flash 7 hasn't reached optimum market penetration yet. Make sure youe publish your Flash in player 6.
Next check to see how Frontpage is embedding the SWF.
You should manually insert the proper HTML generated by Flash.
Unfortunatly Frontpage tends to assume everyone should use Internet Explorer. Mozilla browsers recognize Flash with a different code.
<object classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000"
//Internet Explorer reads SWF here
codebase="https://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=7,0,0,0" width="975" height="500" id="home" align="middle">
<param name="allowScriptAccess" value="sameDomain" />
<param name="movie" value="your.swf" />
<param name="quality" value="high" />
<param name="bgcolor" value="#ffffff" />
//Mozilla browsers need this code format
<embed src="your.swf" quality="high" bgcolor="#ffffff" width="975" height="500" name="home" align="middle" allowScriptAccess="sameDomain" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" />
</object>