Aikido is a martial art that uses the opponent's momentum to defend against an attack. Watch this free video clip as an Aikido expert shows how to defend against a rear wrist grab. Expert: Fred Mastison Bio: Mastison Sensei is an inductee into the United States Martial Arts hall of fame and is a 5th degree black belt who has been active in the martial arts for over 35 years. Filmmaker: Dustin Daniels