I spent about half of last year living at a Buddhist monastery and one of the other people staying for part of that time was a yoga instructor who talked about the same things. I've meditated for some years now and one of the main things he had me pay attention to were the smooth transitions between poses and quality of breath in particular. He seemed to agree with an observation I made about it being much like breath meditation with movement added in. Keeping a steady and concentrated mind with careful movements that flow together with the breath were important to maintain and he only gave me a handful of simple poses to work with, things like just raising and lowering legs and turning my legs to the side. No fancy poses or anything. He talked about the ignorance of many yoga instructors too and how dangerous it can be if not taken slowly and with great care.