I realize this is getting dug up from the archives, but there's a lot more to this story than mentioned here.
You can look it up on the net if anyone wants to read it by searching "txchristopher". he is the guy in the video -- who now sells an aftermarket cure for overheating Durmaxes.
Here's what I know based on reading posts txchristopher wrote on various forums on the net:
He bought that truck new in 2004 or 2005, and immediately began having overheating issues when he used it to tow in the Texas heat. They tried everything from replacing fans to reprogramming, so he used it as he needed, and eventually, it overheated too many times and ruined the engine. GM then replaced the engine, but raised the temps at which the alarms go off for overheating. He had it in to the dealership so many times that they finally told him not to come back as they had done all they could/would do for him. He later started the lawsuit against GM, claiming that the truck couldn't do it's rated load in everyday conditions without overheating. He was within all of his weight limits including GCW and GAWRs with the U haul on his trailer.
There are a number of factors that contribute to the LLY Duramax overheating issue, but to sum it up, it's poor engineering on GMs part. If you want to know all of the details, search for posts on Rv.net by "killerbee" and read the links in his signature. He's an automotive engineer who has picked up the LLY overheating issue as a hobby, and as I understand it as an LLY owner.
Anyway, txchristopher eventually won his lawsuit against GM, was awarded $30,000 and got to keep his truck. It's quite an interesting read.
The video may not be so flattering for the guy, but I admire his willingness to take it all the way (which took years).
It is entertaining to watch the 2nd gen Cummins walk away from his Duramax.
It is also interesting to see how the Duramax tries to "protect itself" from him trying to maintain speed -- first shutting the A/C off, then defueling to lower heat output, and finally going into limp mode.