Flip between full-screen Cover Flow and video in iTunes: "If you are browsing in full-screen Cover Flow mode (View » Cover Flow View, then View » Full Screen) and start watching a video (podcast, movie, music video), you can switch between full-screen Cover Flow mode and full-screen video by pressing Command-Tab"
And I found something these Hint Jockies didn't -- pressing cmd-F (presumably, Full-Screen) does the same thing. How about that?