… "Video Heat Online", a porn site (don’t open it if porn disgusts you).
It also stands for "Vrij Historisch Onderzoek" (which must mean something like "Free Historical Research"), "The World's largest website for Historical Revisionism!".
It's an appropriate coincidence that one finds both sites on the same page when googling for "VHO". After all, "Revisionism" is to historiography what pornography is to eroticism - and that may even be a favorable comparison.