Freestyle ventilation really refers to the knotting of the hairs to the lace.
I'm no expert on this but my understanding is that the individual knots are looser (and possibly a different type) that allows the hair to fall in any direction you want it to or that you comb it.

So its not that the hair is going in random directions, it just means that its able to go in any direction you want to style it in on that day.

When you specify a direction, the knots are tied tighter to a specific side of the lace hole, to make it stay in that direction, although even then, you can force it to go in another direction.