You could do this by , to embedding the <div> tag that is passed as a
parameter to the SWFObject.embedSWF call within another div tag.
Then before I call the SWFObject.embedSWF method, I replace the
innerHTML of the parent tag with a well known value, so every time the
SWFObject.embedSWF() method will find the <div> element in the same
manner it found the first time.
I used this method for changing the movie based on user's activity.
The procedure is explained in the blog post
http://meslie.blogspot.com/2008/07/reload-swfobject-with-different-flv.html