You misunderstand what he’s saying. It’s a very fundamental biology/physiology/brain chemistry, etc. idea that takes some time to understand, if you should so desire. Technically, in the most absolutely biological sense, there is a valid position that states there is no free will. That the precise pattern of the billions or trillions of synaptic connections in the brain form a distinct recipe for a specific behavior in any given scenario.
That being said, despite that it may be valid in one sense, it is just as invalid from the point of view that it is a very simplistic and also arguably not completely informed view. For the most part, therefore, arguing there’s no such thing as free will really is a vapid position, as it eliminates any and all concept of responsibility, of penalty, of society having a framework within which to coexist, and it also stops any discussion in its tracks. I understand the point of view but I find it useless.