To play devil's advocate, what in this video would really train aiki so efficiently that you could learn it in 90 days, or learn it at all? I don't see it.
This is my viewing of it too, although I don't understand the dialogue, so only have my eyes to trust.
I am always wary of any title that purports to give you something in a shorter time than is usually expected.
It seems like many of the illustrated exercises might even teach you the opposite, the habit of keeping your body so rigid that the only thing left to drive the cut is the shoulders, like the man cutting with the sword in the video is doing.
It's hard to know quite how ridgid his body is as it is possible to remain in posture with relaxation, but I completely agree about the cuts coming from the shoulders, apart from the arms it looks like there is no other part of the body being used, apart from being a anchor.
Although videos are interesting to watch and discuss, IMHO the way to learn aiki is to find someone who has it and can do it, then stay with them until you've got it too ( I bet it will take a bit more than 90 days ).