I explained to you why B goes where there is no visible passage. But the fact that B goes in a zigzag was also strange for me. I assumed that B would climb over the fences. But B found an easier way. I think it's due to inertia! B tend to the center of the road, but the side blocks move it to the sides. By inertia, B tends to return to the center of the road and therefore jumps to another fence by inertia. In other words, it is carried sideways.
As for the Z road, it's very interesting. I will try to explain: 1) Central Z , under the feet of B - can't kill B!!! Because they are on an elevated platform!! I have done another demo before in this thread. 2) Side Z is an optical illusion!!! It's hard to explain, I'll take a photo demo... Here is the secret! This is an optical illusion. It seems that Z is close, but in fact it is far away! At a safe distance!!