The baffles (upper and lower) smooth the air flow and direct it across the evaporator or condenser or whatever it is.
The upper cavity in my camper (the space between the top of the fridge cabinet and the cabinet it was put in, had nothing in the way of insulation, just an empty cavern (I stuffed it with fiberglass insulation).
I like the idea of a 12 volt fan in the fridge compartment itself but I don't like poking holes through the inner liner.
I believe the material that the person used in the video to make the upper baffle is Refletix or foil bubble foil that you can buy at Wal-Mart.
