Is there really no way to control audio in embedded video during Keynote playback?

The ability to control media (volume in particular) during Keynote playback seems like such an obvious necessity. Is it really unavailable? The lack of any controls whatsoever over embedded media in Presenter Mode makes using the application extremely difficult for those of us who rely on the otherwise excellent functionality of Keynote. Seems like such a glaring omission, and I'm at a loss to understand the reason Apple would drop that ball, considering we're living in the golden age of media.

Any hacks? I'd be so grateful.