My guess is once he gets past the stuff there's some video footage for, he'll probably make up partially different level design for much of the rest of the game if the project continues. There's no reason to believe any available information exists about what the majority of the game looked like in beta outside Konami's vaults and the developers' brains. So unless he has gained access to either one of those...
Still, it's good to see such a raging interest in during-development material for older games. Stuff like that always fascinates me, but there's never enough of it out there unless a beta cart gets leaked or something. And even then, the copy leaked is often from too close to release for it to be a really interesting alternate version that shows a lot of changes the developers made along the way.
Also, at least to me, it does kinda have value even if he does end up just making up much of the level design. It partially evokes the same feeling you'd get if you really were seeing someone play through a beta copy of the game (well, except for the damn XP pop ins

), even if it isn't one. It also has a somewhat creepy and ethereal air about it with those discolored, artifact-laden sprites and only partially reminiscent level design. In addition to CV4 already having a somewhat creepy atmosphere in places of course.