I really need to know what happened with the landing, because this has been posted multiple times and every time I see it, I think, "I don't know how fast he's going, but it doesn't look sufficient to clear those people with the height of his arc."

Don't be stupid, the four wheeler is coming off the jump at an angle. His trajectory wouldn't put his landing where the clever people are laying down. So regardless of speed, there's no way he could land on them.