I can't understand easily what the artist say. Probably she is saying Hara(abdomen) is connecting physical and spirit. It's called "Tanden" in oriental medicine, right?
In Anatomy, from belly button to spinal through the outside, the muscles are arranged as follows: Rectus abdominis, External oblique muscle, Internal oblique muscle, Transverse abdominis, Quadratus lumborum, Erector spinae. And in the deep in the stomach, there are Psoas major, Iliac muscle, putting the two together Iliopsoas. Any of them is connecting upper and lower body and involved in all body movement. And they involved in breath and blood circulation and autonomic nerves.
That means, as she said, to control this area is very important.
However to control consciously each muscle of this area as to control each finger is very difficult. The motor nerves ain't arranged meticulously in this area.
If you can control, your physical movement revel increase. Because it's difficult.