This video, titled "Nin Nin★TUBE [Hattori Hanzo Ninja Squad Style - Self-Defense Techniques - Hanzo Edition]" (忍ニン★TUBE　[服部半蔵忍者隊流～護身術～　半蔵編]), was released by "Tokugawa Ieyasu and the Hattori Hanzo Ninja Team" (徳川家康と服部半蔵忍者隊).

Tokugawa Ieyasu and Hattori Hanzo Ninja Squad is a group that trains at Nagoya Castle every day to promote "Aichi, the home of the warlords" as a PR team for Aichi's tourism.
The self-defense technique introduced by Hattori Hanzo is said to be a ninja art.

When someone grabs your wrist, you move your arm toward the back of his or her hand in a self-defense technique.
This action makes it difficult for the opponent to grab you (see the video).
The trick to this self-defense technique is to quickly rotate your arm around theirs.