Yes, I do have a fire extinguisher in my truck. Actually, two - one in the cab and another on the pioneer rack. But take notice of where my intake stack is. It is extended up (fording stack). In a real runaway situation, I am skeptical that I - or anyone - could scale the fender, get the mushroom off and empty the fire extinguisher in with tons of black smoke blowing in your face.
This thread has initiated a lot of good discussion about runaways.
Personally, I plan on blocking the 1" port on the air filter cannister and plumbing a CO2 fire extinguisher in to the intake tract somehow. It will be controlled with a valve (or valves) I can reach from the driver's seat or from outside the truck. Or, maybe I will invest in one of those automatic gates (but not sure how they could be triggered on a multi). I guess I could also fabricate a 'damper' in the inlet stack that you can actuate by cable from inside or by moving the lever outside.
Can you imagine a turbo seal letting go when you are on the highway? You could never get the truck stopped in time to run around outside. Maybe turbo seals don't fail when the turbo is running at speed, though.
By the same token, if the truck is idling, say at the fuel stop, and the seal lets go, are you going to be able to scale up into the cab in time to shut it down? Maybe not. That's why I am thinking you need two controls, or maybe one by the e-brake that you can operate either way.
My son also got to exercise his CGI skills. If he had spent more time on the video (and not used a preexisting video someone else made that was not conducive to digital effects) no one would have been able to tell it was not authentic. He's that good, and maybe some day he will augment his income with those skills.
Best of all was the great advice on how to deal with or prevent a runaway. Even better was the brotherhood expressed by the many who immediately offered help. These two things are what this site is mainly about.