This is a crash test of a Mercedes Vito van loaded with a pallet of 1,700-pounds of concrete blocks and hitting a wall at 50km/h (~31MPH). Unsurprisingly to anyone with even a basic understanding of physics, those concrete blocks really want to keep moving after the van stops. Obviously, that driver is going to be feeling it in the morning. And by it I mean clouds under his feet in heaven. So yeah, if you ever find yourself in a van hauling 1,700-pounds of concrete blocks in the back I cannot stress enough how important it is for you to stop that vehicle, get out, and call a friend who owes you a favor and convince them to drive it for you.
Keep going for the full test from all angles.
Thanks to DT, who agrees you definitely shouldn't be traveling over 5km/h with that load.