The Smooth Head Offset Buffer on the First Person View Type is used to move the camera with the head.
I actually also experienced this a few days ago. This was an issue with a low framerate, and will be included in the next update.After i changed it to "0" the jittery was gone, my point is that maybe there's some problem with this parameter that need some attention
I have attached the animation clip and want to move the camera with its head in 1st person mode. You can download this clip and test it,If you can tell me how to reproduce the issue within the demo scene I should be able to help, but without being able to reproduce it I'm not sure why it's not following.