Complex sentence: Some values on each board were marked with an "Extended Play" ribbon; if these amounts were won, any Extended Play players on the team won an additional $500 (later $750), not added to the overall team score.
Split into simpler sentences: Some values on each board were marked with an "Extended Play" ribbon. If these amounts were won, any Extended Play players on the team won an additional $750 (originally $500), not added to the overall team score.