I have a possible solution to the burning bugs the man on the show experienced. I was driving a Ford Bronco when smoke poured out from under the dash. To make a long story short some leaves inside the air ductwork hit the fan speed selector resistor and started to smolder. Evedently the resistors get pretty hot.
Sounds reasonable. Fits the data. Black smoke to due smolder. Fire makes white or grey smoke. Problem did not recur due to consuming the combustables. Smelled like burning paper - leaves? paper? similar material. Both ford products so may use common components.
I had an 80’s Ford F250 that had this problem numerous times. I found that saw dust and wood chips (I worked at a saw mill) would enter into the heater intake. There was a place under the hood in the airbox where there is actually a heating element that I assume was to keep the AC from freezing up, I’m really not sure the purpose. The dust and chips would get caught in this element and actually smolder and smoke. I finally unplugged the element to solve the problem.