To reproduce:
1. Open the attached project;
2. Open "Main Scene" (make sure VR is enabled);
3. Enter Play mode;
4. Try to move around the headset while looking at Plane.

Expected result: Head tracking is smooth.
Actual result: Head tracking is not smooth, you can see the camera is sometimes "jumping".

Note: this does not reproduce in a scene where is no Video Player (you can duplicate the scene and simply delete the Video player from the Hierarchy).

Tested and reproduced on Oculus Rift DK2.

Reproduced on versions: 5.6.5f1, 2017.1.3f1, 2017.2.1p1, 2017.3.0p2, 2018.1.0b2.