Edit: disregard post, I made a mistake.
My own tests of the No intro category have shown that the AI doesn't go properly active until 15 seconds approx, regardless of difficulty. The setup video actually just seems as if the zombies are lunging, but in reality they can't grab. On Nightmare & Inferno mode however the problem is very obvious with the group of zombies before the gate since there are so many of them. For example if you leave subway on Inferno and just walk to the zombie he'll lunge, but not connect until 15 seconds.
I recommend setting the IGT to one minute and just subtracting it, I've tested this out and the AI is fine this way, the first zombie will attack properly if you just walk up to him.
If it's left at zero then all Assisted to Hardcore runs will look legit, but in reality the player had 15 of invulnerability, and all Nightmare & inferno runs will get rejected, as the huge mob of zombies by the gate will make the AI glitch very obvious.
I tested this with both the method shown on slot one, and even temporarily moved my saves out the Steam folder to test it with a brand new setup. Both ways gave the exact same results.
Watch the latest mike wave guide in guides? He says to set it to zero let it run 15 seconds and set it to zero again. Which im guessing kills this problem as he shows after.
Didn't notice the second vid. Thanks for clearing it up.
