Re: Baseline skillset
I completely agree with Mike's post above, and would like to add that while this explanation covers the baseline skills, the 'added extra' that is mentioned and is seen in the clips provided, is in the manipulation of the attacker/uke's ki/intent. This is done before skin touches skin.
Uke's push eminates from the mind, the body provides the 'vehicle' for this to happen. It is this intent that is 'accepted' and 'returned back to' through the medium of the completely co-ordinated mind/ body. In effect the pusher is confronted by their own ki/mind and this at the higher levels is where the seemingly effortless 'bounce' comes from.
Ueshiba, Tohei, Sum and many others have the completely co-ordinated mind body that is the basis for this to happen. When the body is completely relaxed, then the mind is free to manipulate the ki/mind of the incoming attack. If the attackers mind is lead then the body must follow, it doesn''t have alot of choice.
If Aikido practice does not have practice of these co-ordination skills built in, then reaching these higher levels is going to be erratic at best.