To Vacuum Advance or Not to Vacuum Advance

Wait; it idles at like 2" vacuum, and when he shuts it off, it's still at 2" vacuum. I'm skeptical as to what that gauge is actually measuring; I mean where. It doesn't seem to be intake manifold vacuum; the gauge acts more like it's hooked to a cc evacuator system, or IDK the fresh-air intake, ahead of the supercharger.. IDK but I doubt it idles at 2 inches