There are only few direct O-Sensei disciples left alive and Yamada Sensei is one of them. This is one reason he is so respected and demanded. The other and even bigger reason is is his high aikido skill, unique style and colossal contribution to aikido.
If you ever tried to find some good educational videos about ukemi – there’s a good chance that you stopped looking right when Donovans Meeting the Mat explanations were found. This is what happened to me. You may get no idea why it’s attractive but you will get the feel that everything should work just like that because of the softness and smoothness of the moves.