Some times, you need something to overlap (that is, display over) a Flash movie, and seems Flash doesn’t like that. By default. But you can use the parameter “wmode” to change this float-above-all behaviour (which, BTW, doesn’t show the same in all the browsers). The default “wmode”, if not specified, is window. We want it to be opaque or transparent (if transparent, the flash movie won’t have a solid background and you will see whatever is below the flash movie). Of course, the layer which will overlap the Flash movie, must be in a z-index higher than the own Flash movie.
I know this is easy, but there are lots of controversial in the web regarding this topic, so I thought I should clarify it, and also keep this info in this blog for future self-consumption.
This article explains it all in detail and includes examples for all “wmode”s: http://www.communitymx.com/content/article.cfm?cid=e5141
Julio Sancho's Blog 