Did you know that I've had it
is the short form of I've had it up to here
The man is gesturing that he has had enough. His hand is showing that if one could measure the magnitude of a problem, there is no room for more. He is full.
Imagine a problem being poured into a person's body, and keep pouring it in until the level of the problem rises like the level of water when you pour it into a container. The problem rises to the ankles, then the knees, then the thighs, the the hips, then the waist, then the chest, then the shoulders. When it reaches his neck, he makes the gesture of cutting the problem off before the level rises to fill his head up. See how full he is with the problem, it has filled his body, and now he has had enough.