Here's one of the ways to deceive a casino.
Cheats put fake chips with a hidden camera on a table. Next to them they put a cigarette pack with a signal booster. A signal is passed to a monitor of an accessory who is sitting in a car with tinted glass not far from the casino. The accessory relays information and the player hears it in an earphone and he knows what cards the dealer has.
The point is that the camera is located at the level of the table and it shoots cards during dealing.