He demonstrated that in past the Samsung official 45w charger would only super fast charge 2.0 with 5amp cable that was provided with the charger but now he mentioned that 45w charger even with a 25w cable can still do super fast charging 2.0
USB-PD does allow 60w over 3amp cables, which mathematically obviously means the charger will go up to 15v leaving no flexibility outside of safety features shutting it off or lowering the wattage. (Fixed)
With 5amp cables it allows the charger to fluctuate between 9v-15v (or higher) as such allowing the charger to vary it's output to achieve 45w (PPS).
I say or higher as the charger could potentially/theoretically go over 45w to overcome a damaged or aged battery.
That said it'd be uncomfortable running a 3amp cable. The resistance will be higher and as such that charger better have perfect and functional shutoff protection because higher resistance means warmer cables, higher fire potential.
Not giving YOU a electrical lesson, just my thoughts based on what you explained the video demonstrated. So I don't doubt the videos claims, I just wouldn't play that game and thought id explain it for anyone considering it.