Ok, I barely tapped Uke's arm with the corner of my foot.
What would you call this phenomenon?

exact point or precise move?

the arm joint is the weakest on the tori, still gives an epic illusion

Exactly. It's freaking smexy, eh?

I see two possibilities.

1. You didn't realize you had instagibfeet on.
2. It actually looks like a regular decap.

No instagib. Try editing it.

Well, judging by the ghost and force of the kick, I'd say thats a normal decap.

*decap is hitting the head off, your thinking of dm*

Yeah I've noticed this before too. I think it partly has to do with the fact that sometimes your foot can be for a little bit inside of what it is kicking. I have it in taek matches a lot too where my foot will seem to almost miss them but barely tap, and then body slides in half like an old ninja movie ^^

I think its just a good kick... no freakiness here, just a good kick it was going 33, so... good kick