Gotta remember in VR you're seeing two images of the same things, slightly out of phase, one eye at a time. The film viewer will capture the game action and head movements of your headset but does it actually capture and play in VR? No I don't think it does. Think it only does 2D.
You could capture VR as VR with other software and make VR video from that. I know that the oculus software contains a program called mirror that can be config to show one or the other eye or both. Only reason for both I'd imagine is to produce an actual VR video. I capture games on mirror with OBS studio but I only use a single eye view to make vids. Wouldn't know how to make an actual VR video although I'm certain it can be done.
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