Some good information and some misinformation in the OP's video. The presenter brought up some good issues about working loads, loads limits, etc.; however, confused tensile, shear, and bending strength (moment capacity) repeatedly. It appears the hitch in the towing accident broke due to bending or better said, it was a moment failure. The dropped hitch acted like a lever arm and bent, to the point of catastrophic failure, the hitch. The steel was clearly brittle, and should not have been. That appears to be a manufacturer defect. Properly designed structural steel should yield (i.e. bend) before it breaks. Considering it was near the gusset weld, heat might have brittle hardened the steel.
Shear strength is what the hitch pin feels, double shear strength actually, as in two shear planes. Very few factors determine the load capacity: diameter of pin, Fy or yield strength of the steel, usually somewhere between 45-125ksi, thickness of the hitch and receiver steel, and yield strength of hitch and receiver steel. That's it. According to one engineering manual a 5/8" shear pin with mid range steel would be good for 34,000lbs, working load. The shear strength of a 1" bolt, e.g. at the bottom of a 2 5/16" ball is about 44,000 lbs working load. That presenter was not even close when he mentioned the bolt at the base of the ball was a weak link. Keeping a tow strap on a ball is a major safety issue in my opinion.
Tensile strength of steel is what it will break at in tension. Very simply a factor of its cross sectional area and steel strength. For example 1 square inch of 45ksi steel will yield at 45,000lbs - not including safety factors. Even a hollow tube 2" type hitch has a cross sectional area greater than 1 square inch.
In general, a 2 5/16" hitch will handle just about anything you can throw at it assuming the loads are all linear or horizontal. Once moments, angled pulls, and to some degree jerking loads are added to it, all bets are off.
His advice to use a shackle mount hitch is good. It's designed to keep the loads linear with no minimal bending loads and the tow rope cannot fall off the ball.
