The dreaded problem that most web developers come across is the z-index issue with flash elements. When the
wmodeparam is not set, or is set to
window, flash elements will always be on top of your DOM content. No matter what kind of z-index voodoo you attempt, your content will never break through the flash. This is because flash, when in window mode, is actually rendered on a layer above all web content.
There is a lot of chatter about this issue, and the simple solution is to specify the
transparent. This works when you control and deliver the flash content yourself. However, this is not the case for flash ads.
It works reliably in all major browsers, and has no dependencies, so feel free to drop it into your Prototype or jQuery dependent website.