CSS dropdown menu behind a flash video

If you have a CSS drop-down menu, which when expanded goes behind a flash object on your page, for example a youtube video, using the z-index CSS property is not going to help you. What you need to do is to set the wmode attribute of the embed element to "opaque". Here is an example:

<embed wmode="opaque" src="http://www.youtube.com/v/OM_soUJ9In0&hl=en&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344">