I wonder if you are talking about 4th generation Wu style taijiquan master Wu Dakui? In Cantonese his name is pronounced Ng Tai-kwei. A student of a studen of a student of his would be 7th generation Wu.
You may be speaking of another Dai Kui, because there isn't anything on Wu Zongxian's website linking him to Wu Dagui.
I've studied with Wu Dagui's son (Eddie Wu), cousin (Wu Daxin) and sister (Wu Yanxia), and have seen martial demos by Wu Dagui's #1 disciple Tony Chan and his school. They mostly involved hitting the floor over and over, really hard...
The mystical/magical photos on Wu Zongxian's website don't match much that would have come from Wu Dagui's lineage.
http://en.wikipedia.org/wiki/Wu_Dagui