Angle between rotary axis of the rollers and rotary axis of the wheel is 45 deg. At any moment the wheel contacts the ground via at least one point of one among the rollers.
The roller profile is chosen in such a way that the distance from the contact point to the rotary axis of the wheel is constant. So the wheel looks like a round wheel on its side view.
The video shows case when the wheel rotates clockwise. It moves forward and to the left.