We have a customer that wants to open an account for their casino (really slot machines tied to horse racing outcomes). What if any additional information is needed to open this account? It is my understanding that they are not an MSB, but I want to be sure I gather any documentation I would need before proceeding outside of our normal account opening process.

They are a considered a non-bank financial institution. I would start with the examination manual and work your way from there. Make sure you board approved BSA/AML policy addresses opening such accounts. They require significant due diligence.