... you see a gap between two blocks that's maybe an quarter of an inch wide and you shine a light in there, and way back between the two blocks you can see quarry marks...
So you can see quarry marks (not inscriptions!) - nothing unusual about that.
Which doesn't mean that the Khufu cartouche (not in the gap) couldn't have been added much much later :)
And red ocre is red ocre... undatable.
To me, it doesn't prove anything.
The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge.