This is the part the video does not resolve, and to his credit Pager-One doesn't pretend otherwise. He closes the description with respect rather than a claim of discovery: "Major respect to the builders, artists and New Jersey fingerboard community responsible for creating and maintaining this incredible place." No names, no crew, no build timeline. His description trails off mid-sentence asking anyone who knows more about the spot to get in touch.
So the honest state of things: a concrete DIY fingerboard park exists in New Jersey, somebody poured it, somebody maintains it, and the people who did that have not been publicly credited. Nobody has stepped forward in the material we have.
If you're one of them, or you know who is, Kingpin would run that story — the pours, the forms, the edge material, how long it took, how the graffiti and the obstacles ended up sharing the same pillars.