I had a UserControl that I built to add Flash content (not videos) to pages within Sitefinity.
As it turns out, Chrome and Opera browsers were always displaying the Flash on the top, even over the drop-down menus of my RadMenu (Sitefinity Menu).
A quick search yielded a wmode parameter for Flash Player.
http://www.actionscript.org/forums/showthread.php3?t=105396 which sent me to an Adobe page with the code I needed.
For the object tag: