OK, I too was waiting for them to take out the box side/wondering how they get it out. (I would have chained it so I could lower it without dropping, removed it after.)
Ranger in question is Sport = 1,100lb rear springs, subtract the 1,500lb empty weight and payload was only 700lbs to begin with. Someone in video mentions, 1,700 lbs sounds about right - narrower than wheel wells which are 40", shorter than box which is 72" and just over box deep which is 16" puts it somewhere between around 15 ft^3. Using Truckedups, ~130lbs/ft^3 would be in that range.
So, while it overwhelmed the leaf springs of Sport, not near the capacity of the axle. When they finally got it out, springs probably recovered just fine.
Now, the tree in the back of the f100 - that hurt.