According to this site it struggled it lost speed and downshifted which the people on this site identify as the hallmark of a truck struggling on a grade.
Also it is a diesel and didn't go 65 mph up it in overdrive, I have been told over and over on this site that a diesel truck will go 65 up any hill in overdrive with the cruise on.
As far as the driver not knowing the truck, he held it to the floor the whole way, you would hope that the automatic transmission should be smart enough to know the driver wanted max effort.