1. It didn’t look like torture.
2. It’s hard to believe he could only withstand 5 seconds of it (but I’m not getting in line and laying down my money to be next.) I’m just shocked that that’s all it took.
I think it’s simply a reflex, and most of the commentary and explanation in the video was rather fanciful. You have to watch out for this when you snorkel. Normally you’re in the prone position, so no problem, but if you try turning on you back, you can get “water up your nose”, which induces a feeling of panic.
I agree it doesn’t look like much when you watch it.