Not sure of the make-up of joomla but my phpfusion
website hosting has a flash banner in the subheader.php file by inserting this:
PHP Code:
render_header("<center><embed src=lightning.swf
quality=high
pluginspage=http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash type=application/x-shockwave-flash
width=805
height=100
bgcolor=#2E2E2E
scale=showall>
</embed></center>");
the flash is in the root of the
website hosting (lightning.swf) along with it's control file (lightning.txt)
you can see it here
http://www.risk-planetside.com