I've seen this come up many times before, so I thought I would post a thread covering it.

If you have inserted a flash movie into your web page and you would like to make the background transparent here's how...

HTML Code:
<object blah....>
<param name=wmode value=transparent>
<embed wmode=transparent></embed>
This parameter works in IE, Firefox and most popular browsers.

For a more detailed explanation on this subject, take a look at Macromedia's Flash TechNote.

Hope you found this useful