Has anyone heard of Junsado? I rented a video about wrist locks from TotalVid and it starts out talking about Junsado. google turned up this website: http://www.junsado.com/
Sang H Kim, Korean who now lives in the US. Prolific video producer and author of many martial art books (also under the pen name Hanho). I think he is ranked as 8th Dan TKD by the kukkiwon.
I have the video you are referring to.