Miami Beach was another experiment by Bally. In this case, they tried a feature called "Magic Curtains". The bingo card is actually 9x5. By default, only a 5x5 card is shown, and as you insert coins, you may reveal additional sections of the card.
As you do this, other features may be revealed.
Advancing odds, extra balls, 'corners scoring' (not exactly), 3 scores as 4 or 5, and great artwork.
Backglass (Curtain in default position):
Backglass (Curtain in expanded position):