Why would this guy hit the ground and immediately start snoring (see video)?

Probably knocked himself out cold..Or probably suffers from Narcolepsy.

Some people with a serious head injury will do this. it depends on the seriousnes of the injury. my daughter did this in an auto accident. she was not wearing a seat belt, in the back seat, and her head hit the door glass, from the inside, on impact with a telephone pole. we did not understand this either, until a doctor informed us that this is a sign of a serious injury to the brain. she is okay now.

Probably for the same reason he snores when he sleeps; he is unconscious, allowing the soft tissue in the throat to relax and vibrate when he breathes.

I found this discussion about a similar situation, maybe a third of the way down the page, regarding a guy who apparently gets pretty beat up in a fight (the video they are referring to is no longer available and I don’t think I would have wanted to see it anyway) but a couple of the posters make some interesting points. One says:

“I’m pretty sure that wasn’t snoring. That was an unconcious man trying to breathe normally with a broken face, probably nasal cavity.”

And another poster mentions that it’s not so much snoring as it is the person trying to breath through a broken nose/face.

Not sure about any of that but it kind of makes sense, I think.

How is my opinion that he is faking it, off topic in any way? why is that moderated?

Narcoleptics are not like they’re portrayed on TV and in movies. They don’t go from awake and alert to fast asleep in the blink of an eye.

I agree with the other posters – he probably got knocked out and began snoring either because of some facial trauma or just muscle relaxation which would lead to snoring while sleeping.