Blending may look nice and aiki' esque.... but sometimes, a block is more simple and direct and less energy spend vis-a-vis blending/tenkan. If you notice carefully, the Karate-do sensei did not just block as in dead-block, he actually parry/deflect.
Yes, he did. But still ...
Can you please elaborate on the zero-effort comment? Thanks.
In person, I could teach it to you in 30 secs. It is impossible to explain ...
But let's try: Basically, your arm is totally relaxed - but almost in position - and when the strike approaches you energise your arm by extending it slightly and hit the strike. It should look like a block, but it is infact a hit. If you do it direct, then it is a hit/block - and takes no efort at all. The harder he hits you the more it hurts him - as long as your timing is perfect. If you do it within circular Aikido movement then, it is still a kind of hit (but less of a block because you moved). This is not what they do in Karate.
Oh, and this hit/block is forward - like in Aikido, not sideways - like in Karate.