Well I suppose it's not the actual effects of the video. But the emotional touch it has. Sure, the game might be complete and total crap or not. But the trailer sure is nice and makes you wonder what the actual game will be like if the trailer is on such a level to touch you emotionally.
And the trailer does give signs of what the actual storyline may be. Obviously there is somehow an outbreak on a tropical resort island that this family has gone to, maybe for spring break or summer. And it is about in the mid of the vacation and the outbreak actually hits then. There are also hints of what the zombies may or may not be like and look like. There are also possibly nude zombies (See tropical resort with tanning!). If that's your thing, I'm not gonna judge. It's cool.
We also all may be mesmerized by this trailer because it's better than other trailers for new games lately. It's a breath of fresh air for some.
From: Harry
I personally don't find it amazing. It's nice and emotional that he tried to save the girl and everything, but there aren't many redeeming qualities in the video other than that. If you watch the linear cut, you'll probably not be as impressed. It's just a girl that turns into a zombie, bites her dad, and falls out a window; but all in reverse slow motion. Why is everyone so easily impressed over this? Reverse slow-mo trailers have been done before (see Tomb Raider), there is nothing indicative of the game, etc.