Not sure thats quite it...
I'd like to know how you actually get it to work in the browser window. It might even be a Dreamweaver question?
Do you make your movie transparent and place it on a higher level above the main page content somewhere?
Is this the way to go. Go to Html options in Movie properties and set Window mode to Transparent windowless?
then the background is transparent?
Transparent, layered Flash ads
I stumbled across your topic while looking for the exact same information. It is more than simply playing a transparent .swf. I grabbed all the code and .js files from the Ice Age ad that played on Yahoo a few weeks back and it is some brutal stuff. They did a lot of setting and checking for cookies to determine when you would see it but once you strip this stuff away, it appears that they are checking your browser and if you are running IE (which supports transparent .swf's) it generates a layer on the fly and then plays the .swf in it. Unfortunately, there are some pieces in the code that, as of writing this, have thwarted me from recreating the effect. I think parts of it might be proprietary (they definitely point to URLs I'm not allowed to snoop thru) -- which of course doesn't mean that it couldn't be reproduced in other ways.
If you get ANY direction on this (even what these types of ads are called in the industry), I would love to hear about it.