Here's an exercise. Go to the App Store, click on Top Grossing. Out of the 150 apps displayed, how many are gaming-related? I counted 113. Thats 75%. I don't have the charts but you can compare this to a year ago period. My guess is that percentage has grown. This is not an accident.
He's not talking about FB gaming. He's talking about mobile games.
Mobile games that are not played on Facebook are paying Facebook for ad space so that they can reel in additional whales. Games like Clash of Clans & Gears of War.