Be aware that despite wearing suits, they are talking about this in a joking, ironic way, talking informally, and using many analogies and figures of speech. By "the hydraulics" I think they mean the kind of hydraulic lifts used in car repair shops. These hydraulic lifts can exert huge amounts of upward force. They are almost irresistible. To "stick something under it" means to act quickly, vigorously, and not very carefully. He means that they are going to raise interest rates on certain kinds of loans "with hydraulics." That meaning they are going to use their economic power forcefully, and there's nothing much the people who want these loans can do except pay that interest rate.

To "stick the hydraulics under something" means to raise something or to make something go up. In this case they are talking about interest rates.