I've been playing with the camera movement and there is one thing I can't figure out. I only used one tool to set the keyframes and that is Camera zoom. The background picture shouldn't change with any camera movement, that's why I ticked in the layer panel 'Immune to camera movement'. But that works only partly. Tracking Zoom will scale the picture. That 'Immune...' is (partly) effective, you can see when you turn it on. Just check out the video. Is there something else to tick to stop the picture from moving?
You have the rotate to face camera option checked. You don't want this. Un-check it and the immune from camera movement should be working properly now.
Indeed, that solved it. I don't understand why it would scale then, as I would think that "immune to camera movement" should do the trick. What does "rotate to face camera" do?