The video is set at a rate about 10 times faster than real and represents a ZBrush session lasting about 20 minutes.
In order to set a pose for a hand, we use the Transpose tools provided by ZBrush, along with the ability to mask part of the mesh according to his topology. In this procedure we begin working on a mesh with a rather low level of subdivision. So we set a mask near a joint, make it more pronounced, and then apply a rotation to be adjusted, usually with a small shift. Once the rotation has been applied to the limb, we move to a higher level of subdivision and adjust the pose with traditional sculpting tools. In the video, the process is repeated several times in order to pose the hand and fingers.