And per request via PM. Here are the screenshots. I'll walk you through them as well.
This is the standard cockpit view. Note the horizon line extending from the target reticle.

This shot shows how the horizon line tilts when you tilt your chopper.

Most people leave it at that. The horizon line bar is there to do nothing more than to show you which way you're tilted, so that you can regain balance and hover when necessary. This isn't the case.
As you can see in this shot, when I'm pointing my nose down to close in on the jets, that horizon line leaves the midpoint of my target reticle and moves up. This is because the horizon line also acts as your missile placement on the Y axis.


The trick to firing these missiles is to use the target reticle to judge where on the X axis (Horizontally) your missiles will go, then using that horizon line to determine where they'll actually land in regard to distance.
Here's a colored pic to describe it visually. Picture this in your mind. Your crosshair isn't your center target reticle, your crosshair is dynamic in regard to your horizon line position, and your center reticle. The purple dot is about where you should hit.

A couple things to keep in mind:
1. Turning the chopper left or right throws everything off. The key is coming in straight, don't bother firing while turning unless you've got a LOT of practice doing it.
2. Everyone's video settings are different. There's no way to determine 100% where you need to aim based on someone else's screenshots. It's the same with the TV missile. Find your own sweet spot.