people have sent us hate mail and things like that. >> national association of karate and marshal arts schools. nightingale's gym is not part of it. >> to not encourage or allow children and those under the age of 18 to participate in cage fighting especially on a competitive level. >> he's an advocate of the sport, but horrified by the video. >> two children engaged in this activity, which the dangers to them. from a physical perspective and from an emotional, mental perspective. if they were wearing head guards and maybe we could then say, okay, this is safe. but we've seen clear, too dangerous, too risky.