if you are in control performing the moves, and the GLOC blackout tunnel begins, you can release the pressure and restore normality almost instantly. if your a passenger, all you can do is squeeze harder and hope the tunnel doesn't get longer until its lights out.
a short quick 8G is not lights out territory if you have been at 1G previously, but the "slalom" move before the big pull made sure he went out real quick, all those sharp turns started the blood south long before the 8G.