The above answer is actually incorrect: the view is not private, and you can add views to it. You just have to dive deep enough to find it.
For example, in iOS 5.1, you can try something like this:
UIView *fullscreenOverlayView = [[[[[[[mpPlayer view] subviews] objectAtIndex:0] subviews] objectAtIndex:0] subviews] objectAtIndex:2];
[fullscreenOverlayView addSubview:ccButton];
This will add a CC button to the view, and if you specify the correct value for the frame of the CC button, it will insert the button to the control panel, and hide/show it with the control panel on touch. FYI: this is the frame I use:
BOOL isPortrait = UIInterfaceOrientationIsPortrait([UIApplication sharedApplication].statusBarOrientation);
// all of these values are just based on measurement on screen
// to make sure that the CC button "seems" to be part of the player s control panel
if (isPortrait)
{
return CGRectMake(222, 880, 40, 40);
}
else {
return CGRectMake(350, 625, 40, 40);
}
NOTE: the set of subviews of [mpPlayer view] are different for different iOS versions, so consider this as a work around only. There s no guarantee that this will work on iOS 6, and will crash on iOS 4.3.