In the lower left corner of the app, MC, where the action window is.
Have another look at Adam's video..
https://vimeo.com/101559696Once he begins playback, the display window opens, with cover art (because that's how he has his set).
In the video, he minimises and maximises the display window to show you exactly what he is talking about.
Note that if you have the tag window open at the time you begin playback, the display window should still open, but will not replace the open tag window (because that would be annoying if you were working in there at the time). In those cases, you would expand the display window yourself, manually, as Adam demonstrated.
If you are playing audio and not getting the display window, something obscure is wrong. I say obscure as there would a lot of noise here if the display window had gone AWOL for many users. There's no setting for it. It's appearance during audio playback is default behaviour with no options controlling it, other than what it actually displays, as shown in my screenshot.
-marko