Re: What are these things
That is known as "Weight Distribution." Basically, it works like the handles on a wheelbarrel. The chains pick up on the ends of the bars that are attached to the hitch. The hitch then torques around, forcing the load of the tongue farther forward on the tow vehicle.
This particular system is also sporting the sway control. It is just barely visible on the passenger side. It is essentially a "friction brake" that works between the side of the tongue of the trailer and the hitch. When the trailer "fishtails," (sways), the sway control basically provides resistance so it can't fishtail as much. A properly set up weight distribution hitch can help a little bit with sway, but not as much as a proper sway control.
These hitches are pretty near and dear to me, and I don't have to pretend to know a lot (but not everything, of course) of what there is to know about them. This particular system appears to be Reese brand, notable by the drawbar shape, pitch control, and flares at the end of the bars by the chains. Advantage of flairs: easier upgrade to a dual-cam setup, which combines with some other parts to become an anti-sway setup. The system he is using retails for around $450, assuming it is a Reese setup.
It looks like the snap brackets on the tongue are a little far forward, assuming the trailer and truck are in a straight line. When the truck and trailer are aligned straight, the chains should be vertical, and the tails of the bars should be about 1/2 way (general guideline I use) between the ground and the bottom of the frame. The trailer itself should run level or just slightly downhill in the front. Just a few inches up or down can greatly affect the handling of the trailer no matter what hitch type is being used.
