He puts the end of Western Civilization in the Museum of Mosul, where ISIS thugs destroyed timeless treasures, blowing up places of worship, and burning libraries.
I would have put it in the 2008 election of Barack Hussein Obama as President of the United States; but that's a detail. Western Civilization has been in decline since the Endarkenment, better known as the so-called "Enlightenment."
There were many milestones along the way, as there will doubtless be others. But we have for some time now been well into a new Dark Ages far more bleak that those following the "Fall of Rome" in AD 476. We just haven't quite realized it yet.