building a video plugin

I have started building a simple video plugin for version 2 that will allow mov, wma, rmv and maybe flv to be added to the editor.

The problem I'm having is that I can't seem to work out how to add an element inside an element.

I actually got it working in Firefox using CreateElement and appendChild but it won't work in ie.

at the moment my wonderful hack job is here.. http://dev.peaksoftware.com.au/test.php

If you try out what i have so far you can see that the object tag is working fine (only add mov tag at the moment).

What is the proper way to add a param tag to the object tag?