This is interesting because I was considering cloning my own voice as a way to record things without the inevitable hesitations, ums, errs, and stumbling over my words. By this standard I am allowed to do so.
But then I thought what does it even mean "someone else's" when multiple people can make a video, if my wife and I make a video together can we not then use my recorded voice because to her my voice is someone else.
I suspect all of these rules will have similar edge cases and a wide penumbra where arbitrary rulings will be autocratically applied.