For me, it's the finger in the holy water that strikes the deepest. Maybe I'm misinterpreting it, but to me it spoke to that moment when I realized that the still-festering injuries of original sin remaining in me can infect even what seems to be otherwise devout behavior. For me, that's the experience that began to teach me the nature of real compunction, and helped me at least begin to taste the surrender of repentance.
Plus, I also realize that the confessional in the video reminds me a little of the one in which I made my first confession, only a week and two hours after I was baptized. I was exceedingly nervous and ashamed for having made such a mess of my grand experiment in such a short time. The old priest was so kind. That moment has been an enduring image of God for me over the years.