Howard Webb's half-time analysis of the officials' performances pretty much tells you all you need to know about the implementation of the video referral system.
Premeditated assault on Silva - "It's too early in the game to give a yellow"
Aguero penalty - "There was a slight touch but I can understand why the ref didn't give the penalty"
The award of the goal kick - "All I can say is that at the time he must've been certain that the whole of the ball went out or he wouldn't have given it"
Sanchez penalty - "Yeah, that's a definite penalty, I'd have given that one"
AND all the linesmen have to do is flag for offside when they're "not sure", the game then stops and we're left complaining (again) after the video shows that Aguero/Sane/Sterling/etc WAS actually onside, but what're you going to do about it?
Don't hold your breath for video reffing to sort ANYTHING out because it simply will not.