The thing I've noticed about Cubs is that they run out of traction before they run out of power. Give a CC the same tires (and I bet they're filled) and plow and she'd run side by side with that JD.
That said, AWESOME job the owner did. That machine sounds sweet pulling the plow through the ground in the video. Green or not, I'd be proud to have that in my garage next to my Cubs
Edit: "The tractor isn't exactly a stock tractor anymore we got a 4 cylinder outboard Crosley engine and replaced the original. The engine runs about 55-60 horsepower." I'd say it's not stock!!