That means that if you ask 10 people and 9 say that the ball touched the ground but the last guy can't tell, then the play stands.  The fact that we're still arguing about the call definitely means that the call should have stood.

The clarification of the rule a few years ago said that any review that takes more than 2 minutes is an indication that the ruling on the field should stand.  If the argument of the review continues for days on the social media, that's another indication that the ruling should stand.

The problem with the video is exactly that the ball can't be seen hitting the ground.  It's like playing tennis with someone who catches the ball before it hits the ground and then calls the ball out, claiming that it was "obvious."  If people can't see the ball hitting the ground, it's not obvious.