This specific bug is fixed in version 1.4.0.31 (Steam). TrackIR now behaves more as expected, but it doesn't work "out of the box". 1x sensitivity reduces your range of motion. I also set mine to 10x and it now behaves as expected.

I'm having the same issue. If I turn my head using trackIR and then zoom in with focus, the camera position changes as shown in the second video above. Turn your head to a specific point, usually further away from center screen the more obvious the issue becomes. Then zoom in with focus/right click, and your zoom will be in a different location than where you were looking. Zoom out/release focus and your camera will go back to it's original location. Specifically very inconvenient when flying helicopters, looking around and zooming in to try and spot infantry.