Thanks for posting that video. Very interesting.
I have to ask, is this considered an advanced technique? I ask because it's part of the normal curriculum at my dojo. We also practice a type of counter punch that turns a block into a punch, in the case that you can't or don't slip the punch. You block and continue the motion, so that a middle body block, for example, becomes a lunge punch, or a vertical backfist is first used to block a punch and then the backfist is delivered to the bridge of the nose.
Is this really considered a 'lost art'? Sometimes I feel I must extraordinarily fortunate to have found the dojo where I train.
I will say that our combinations following the counter punch are different-looking, but I presume that's down to differences in style between kenpo and isshinryu.
Thanks again for posting that.