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Aikido
Morihei Ueshiba is referred to as "O sensei". He is the founder of Aikido.
The videos are very old and takes a long time to load. I suggest you buffer the video while reading his information on wikipedia.
Here is the wikipedia's information.
Other interest stories of the founder:
Aikidoonline
Wikipedia - Koichi Tohei (founder of Ki Society), on how he started with Aikido.