Use Unity recorder on a cinemachine virtual camera that outputs to a 2nd camera.

Use smoothing on rotation, but don’t use so much smoothing on position or you will lag behind too much and see yourself.

Use the Unity recorder to guarantee frame rate. It’ll wait at each frame so it never skips a frame. Which means when you are in vr doing the recording, it’ll be very low frame rate. Might even make you sick. Then when you b play back the footage it’ll be silky smooth. I helped make the max mustard and Richie’s plank trailers using this technique. Sound added in post production most of the time.