Hi fazu, I spent several years in Guam one week at Anderson AFB
BEST is an acronym for Biomechanically Efficient Shooting Technique and YES, it is the technique that KiSik Lee has defined in his books. They are rather expensive and if I was to get just one,
"Total Archery -- Inside the Archer" is the one! It IS definitely a target archery oriented book but it has all the elements of form that can be adapted to your own shooting style.
I have spent most of my retired life learning this style and trying to adapt it to a useable form for us traditional shooters. I use this basic and try to adjust what is taught there to the styles I've learned from Asbel, Hamm, Ferguson, Wesley and Jenkins. What I show on the video is probably not exactly what BEST really wants to see but as I say, I've tried to demonstrate a way that gets traditional shooters into their back muscles in a most efficient and repeatable way. Once you have learned the FEEL of really being in the back you don't have to be as exaggerated as in the video. It is simply a way to get that feel.
Depending on what type of shooting you want to do, it (Total Archery) will give you form basics and the reason why and you can pick and choose any part that works for you. I will say that it is a system that is proven to REDUCE common archery injuries. You cannot avoid injury if you are doing anything at all but reducing them I would think is a plus.
Glad you got something out of the video and let us know how it is going from time to time.