I think the scam here is like the scam they did with Keno. The guy is adding up the score incorrectly (you have to see the last few seconds of the video where they challenge him) so he basically gets the maths wrong and lets them win the first few times, then he would go on to give them the true total, which will always mean they lose, subseuqently. It looks like a more complicated version of Keno, certainly I can imagine if you had a few drinks inside you this would be very difficult to understand.
My advice to the OP is to contact the Dominican Republic Tourist Office in your home country and tell them about this. They will take you seriously, they hate bad publicity for Dom Rep, and they will definitely have relationships with the resort involved. If any tourist is scammed, this is always a good thing to do. There is DR Tourist Office in most countries that send large numbers of tourists to the island.