o.k., if you watch the first 5 seconds of the throws in tachiwaza, you will see o'sensei doing ikkyo omote the way he wanted it, quite exaggerated, but still, along the way that he wanted it done, he wanted you to actually enter uke's attack, and stretch his loins. There were a lot of other tricks to keep uke in place, such as stepping on his forward foot. This is quite different than the ikkyo omote used in almost all aikido dojos today.
Another, favorite saying of o'sensei was 'Even I don't know if I'm doing ikkyo omote right.'
I guess what is seen in the youtube clip is ikkyo omote ki no nagare (with a throw) prewar style aiki budo. I believe it was not originally taught the way it is demonstrated here which is indeed very high level. Chances are also that Oīsensei altered the technique later on, at least Aikido as we know it today
(in all itīs various shapes and sizes) didnīt exist in itīs modern form(s) in 1935 even the basic elements are evident in this video.
In Budo, the edition that Aikidojournal published all the different basic techniques are discussed and there are also a dvd available where Morihiro Saito Shihan demonstrates the various Aiki budo techniques the way he was
taught. Very interresting indeed.
I also hear that many assumptions on aikido techniques comes from watching Oīsensei performing in flowing form and itīs clear that the basic elements of each technique are not visible to the naked eye.
Adding sword and staff to aikido came later and the teaching methods evolved as well.
And what is shown is the highest possible level which Oīsensei later on referred to as Takemusu Aikido.
Thats why we need to trust Oīsenseis students and their students when they tell us what the basic forms look like. Itīs not possible to judge by simply watching a couple of youtube clips with Oīsensei demonstrating his techniques.
Personally I go for those lineages that have a long lasting "personal" relationship with Oīsensei but this doesnīt mean I reject anything as being invalid or false just because it canīt be proved to be historically correct.
But again itīs hard to prove scientifically what is auenthentic, but ongoing historical research does point in certain directions I believe.
Itīs interresting to read Ellis Amdur and Peter Goldsbury and I also like very much to read Stanley Pranin but offcourse also the second Doshuīs book "A life in Aikido" is highly interresting I feel.