From my understanding, setting wmode to transparent creates harsh performance detriments.
The contents of the SWF are drawn over top of the elements on the page, once per interval. In essence, it is running outside of the browser.
I've had experiences where wmode="transparent" would effect the SWF if I were CTRL+TABing through Firefox's tabs. The SWF would not engage as no official focus had been set because it seems that it is actually "floating" over the page, rather than residing in it.
For Flash games or other page content, I agree that the performance impact of wmode=transparent is to be avoided. But Flash ads are a different story.
FlashHeed is designed to be used specifically on Flash ads that you don't control. If you're embedding rich content on your page (like Flash games) where performance matters, you'll write your own embed tag and can control the wmode directly.
The contents of the SWF are drawn over top of the elements on the page, once per interval. In essence, it is running outside of the browser.
I've had experiences where wmode="transparent" would effect the SWF if I were CTRL+TABing through Firefox's tabs. The SWF would not engage as no official focus had been set because it seems that it is actually "floating" over the page, rather than residing in it.
FlashHeed is probably a bad idea.