I had a couple of experiences in a Chinese section of Malacca, Malaysia, that threw my skeptic mind for a loop. I was sitting in an outdoor cafe, sipping an iced coffee, thinking, "Gee, I really want an orange right now." Not 5 seconds later, a man walked up to me, proffered an orange, and said, "Happy new year." I knew better than to believe in hocus pocus, but yowza. Anyway, please avoid bludgeoning people.
I think Hu's explanation should be sufficient here, minus the hickory-dickory-doo about qi - that he hardens various body parts by repeatedly striking them over time. For most of my life, I have done this with the bones in my hands, incurring hairline fractures that heal and produce harder bones. I rarely have occasion to do it, and I'm no exhibitionist, but this has enabled me to throw my fist into some unadvisably-dense objects. My dominant hand's bones are noticeably harder than my other's, as it has gotten more attention. Btw, I'm no Shaolin monk, I'm just foolish.
He appears to be pressing the drill into the squamous part of the temporal bone (side of skull), close to where it articulates with the greater wing of the sphenoid bone; this area can be relatively thick. As for the excessive exertion on the jugular notch area, uh, I dunno.