Hi Eugene,
IMO, for a beginner approaching the study of Qigong, it is best to get the external structural components correct before worrying about the internal organs and meridian lines and what they would do, because if the external movements are done correctly then the internal will kick in automatically through the breath.
This movement puts its emphasis on the rotation of the cervical and thoracic vertebra as well as the vertebra of the waist. Through turning and rotating, the blood and the fluid circulation will improve and at the same time the internal organs located in the upper and middle part of the body, like the lung and the heart, will get their internal massage.
By stretching and relaxing and by expanding and contracting the chest and the arms, the lung and the heart will be strengthened as well as the muscular and skeletal components, helping to prevent rheumatic trouble of the joints and four limbs..
The substantial and the insubstantial repetitions of rotating and stretching the body from side to side not only help to strengthen the leg muscles but also help to improve alignment of the shoulders, the back and the hip, preventing any chronic back problems from arising, but only if the movements are done correctly, otherwise more harm is done than good.
Particular attention should be paid not to stress the knees out by pushing them too far forward, or tilting the back too far forward or backward, thus losing the stability and the alignment of the bogy. My take is to work with the seen before worrying about the unseen and work with the structural before worrying about the medical.
Visual comparison is the best way to gain some insights into the working of Qigong, people may tell you lies but their body cannot, we can read their body and be able to see if they are telling the truth or just being the great pretender with their flowery words and acupuncture charts.