Please see the picture. After pressing the fullscreen button, the webview maximizes behind the UIPopover. 

I tried to look out for MPMoviePlayerDidEnterFullscreenNotification, no luck.
I really don't want to ship my own UIPopoverController but this is my only "solution" at the moment. Using anything other than UIWebView is also not an option, as I am displaying YouTube-Movies.
Edit: I use a UIWebView, so there is no way to access the views/classes that are used internally.
 
     
     
    