Re: O Sensei observation
Interesting thread. I would say it does show his preference for kokyu myself.
As for correct timing then obviously yes for that's all part and parcel of good Aikido. If timing was out it would have the same effect as when any principle is out----trouble.
As for yin and yang, the basics of, well then that's obviously there too but it's there in every movement and technique in Aikido so it's not a particular sign of said videos.