As someone who has been on the fringes of internal martial arts for many years, mainly because I have had friends who were martial arts journalsists or high level internal martial artists themselves, I have had the good fortune to be around a number of so called masters of internal martial arts, and seen them teach and explain their material.
In case anyone here is wondering...and doesn't already know...the material being presented here would quite likely have been considered very high level, secret, and would probably not have been available to anyone except a "disciple," or a prospect for the next lineage holder. And even then, not many people who actually know the "secrets," to their art, are necessarily capable of teaching it efficiently and succinctly.
Thank you Sifu Kelley, GM Sam F.S. Chin, and all those responsible for making this so readily available to us.