Does this bug affect everyone? Try installing said pathetic excuse for a media player, and then in ‘Player Preferences’ untick ‘Show Content Guide at startup’. Exit and reopen the program, then try to maximise or resize it. If you’re getting the same result as me, you’ll know instantly that Apple have screwed this one up pretty badly.
"Please give me 3-5 minutes more. My manager is having issues with her tool."