But he dropped his hands to block low to mid and the kick went high towards his temple in an oval loop.
Correct because he didn't understand the kick. For example, the correct defensive response to a low kick is not to drop your guard from your head, to try and stop a low kick with your hands.
So you think that a blindspot is a complete, 100%, perfect, blind area? C'mon. How is this even possible
if 2 people are standing in front of each other, fighting?
Yes. The back of your head is a blind spot. 100% meaning that you cannot see the back of your head without the use of something reflective like 2 mirrors.
Human visual range is around 180 degrees horizontal which means you can see what is on the side of your head.
Test: Have someone stand next to you on your right side and left sid. Keep your head straight and only move your eyes to view the person standing next to you. Most people should be able to see the person standing. Now have the two people step back a little and repeat the test. As long as you can see them with out turning your head or neck then they are still within your visual range. If you don't see them then they are 100% outside of your visual range and 100% in your blindspot. The fact that you can't see them 100% means that they are in your blind spot 100%
Closing one of your eyes creates a blind spot and no matter how you focus the open eye you'll never be able to see what is in that blindspot. When you move your head, that blindspot is still at the same angle with the exception that now a different object is in the blind spot. Do some research on Peripheral Vision for the human eye and you'll see just how wide visual range is. So the answer your question is there a 100% perfect blind area? yes.
Another trick that you can do to experience your blind spot is to hold your arms straight out to the side and slowly move your arms backwards while looking straight forward. When you can no longer see your fingers wiggle then it's because they are in your blind spot. This is important because if I'm facing you then it's really difficult for my opponent to get into my blind spot. Fighters are always told to keep their eyes on the opponent because looking down or away puts the opponent into the blind spot and usually exposes the back of the head.
Blindspots work horizontal and vertical. If you watch the video in slow motion you'll see that he drops his guard while the kick is still in front of him and well within is visual range which is why he reacted to the kick in the first place. Had the kick truly been in his blind spot then he wouldn't reacted to the kick at all.
This is a kick that appears to be in this person's blind spot. Notice the reaction to the kick is totally different than the video that you showed. In this video he doesn't react at all to the kick which makes me think that this kick was 1. in his blind spot because it landed under his chin, we can't see under our face and that's where the foot came from. In this scenario he probably saw something that looked like a kick then it disappeared out of his vision making him think that nothing was coming which is why there was no effort to defend the kick he couldn't see. My other guess is that he had tunnel vision to the point where he ignored any other movement. Maybe he was so focused on his hands that he couldn't see anything else aka "Tunnel Vision."