This is not a credible source. Yoga is less efficient in terms of the benefits you get out of it per time spent when compared to other activities (like high-intensity activities).
The Tibetans are fairly high intensity, at least by my non-athletic standards. Doing 21 reps of sitting to table position is some degree of work.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.