So after more research, this appears to be some form of arm deflections, not hand deflections. This vid shows some good examples:
Seems pretty realistic if the attacker committed. Probably less so if they did not throw a heavy punch.
To put that move in more formal terms, if one cares -- it strings two basic movement variants in a manner of henkawaza:
1) It begins as an ikkyo engagement of the punch. It treats nage's arm as foreshortened (as though with stubby elbow-length arms) but the tai sabaki of it is ikkyo
2) The follow-up change in the backfist (metsubushi?) is a manner of straight entering kokyunage, (and the tai sabaki is equally primed to invert for an ikkyo engagement of the (not unlikely) off-hand counterpunch by uke)
3) The final movement variants seem to illustrate that if entry is too impeded for the full kokyunage insertion, there are options (in the exact same mode of throw) to:
a) buckle his structure rolling/striking the shoulder back, or
b) following the leading arm flow around, down and into the arm-wrapped kotegaeshi
The two basic tai sabaki principles are present -- The first closing the body from the outside of the strike, the second opening the body into two possible forms of kokyu throw and the last of that variant (the formal kotegaeshi) then reversing to close the body once again.
In all the options -- only the range and manner of engagement allowed by the circumstance really change. The tai sabaki is simple and spindle-like, in the manner of a "prayer drum" with the in-yo close-open-close etc. of the frame in concert with the progressive irimi-tenkan of the movements.
Key thing is IMO, that one does not, cannot, plan this or train this precise engagement -- it evolves completely from the first principles expressed from the body in course of the physical engagement itself.
Aikido is (or ought to be) an extensive training mode for discovering, learning and expressing those first principles of this manner of action, not a collection of mere "techniques." Looking at it the first way makes it plainly martially effective and profound. Looking at it the second way makes it seem trite and utterly lacking.
This difference of perception in the purpose and intent of the art is fundamental to these sorts of debates, it seems to me.