Indeed, this doesn't show which truck is more powerful / greater torque. It shows which truck is better at towing, which is arguably more relevant for a truck. Greater mass also means greater control while towing.
From the video you see the front wheels rolling back, rather than trying to grip forward. This was rear wheel drive.
Engineering Explain has a fantastic whiteboard breakdown of the maths: https://www.youtube.com/watch?v=jzKCJsou10w
A more relatively massive truck also helps reduce the propensity for jackknifing.