I haven't watched the video but from a Chinese Medicine point of view, the period comes about as a natural cycle of old blood being flushed from the penetrating vessel (runs up the inside of the spine, strongly related to blood) on a cyclic basis to prepare the body for new blood to be made.
As a woman's body is built primarily on blood and yin (as opposed to men who are beings of qi and yang), it's important to have a significant movement of blood each month to enable the body to build new blood.
As qi and blood are closely related, and qi corresponds to mental emotional energy, so too old mental emotional energy flushes with the period, eliminating and moving on stuck emotions from the month. This is why some women experience a range of emotions during menstruation.
Of course pathology is more obvious during this time of movement, such as severe cramping or stabbing pains and other symptoms which can indicate an imbalance - of course the beauty of this indication is that there is a treatment option, it doesn't have to be a life sentence..