The story that goes with the video may be read here. This video comes as little surpise to the parents of twins. When my wife was carrying our twin boys she often placed my hand on her womb as our lads were obviously having fun playing with each other. Of course people have been aware of this as long as there have been people:
21 And Isaac intreated the Lord for his wife, because she was barren: and the Lord was intreated of him, and Rebekah his wife conceived.
22 And the children struggled together within her; and she said, If it be so, why am I thus? And she went to enquire of the Lord.
23 And the Lord said unto her, Two nations are in thy womb, and two manner of people shall be separated from thy bowels; and the one people shall be stronger than the other people; and the elder shall serve the younger.