Excerpt from Wikipedia. Comments in [brackets] are mine.
The Shuni-e (修二会, literally “Second-Month Service”) is a ceremony held each year at certain Buddhist temples in Japan. One of the popularly known Shuni-e is the one at Tōdai-ji in Nara, held between March 1 and the morning of March 15 [the one in my post!].
The Tōdai-ji Shuni-e ceremony was originally started by Jitchū, a monk of the Kegon school, as a devotion and confession to the Bodhisattva Kannon [better known as the Goddess of Mercy]. It has continued every year since 752.
The ceremony actually comprises an array of ceremonies centered on repentance to the Bodhisattva Kannon and prayers for the welfare of society.
Two of the best known ceremonies of the Shuni-e are the Fire Ceremony (otaimatsu in Japanese) [which is what you see in my videos] and the Omizutori, or “Water Ceremony” [which will happen on 12 March 2016].