Looks like a bunch of hokus-pokus.
1) A single given thread only uses one core at a time... somehow "forcing all cores to run" is not going to speed up that single program you are running. (like a game) If anything it will tie up resources unnecessarily and slow down the thread that requires the most attention.
2) It looks like what he's doing is disabling any power saving in his laptop. This is a terrible terrible idea.
- If you've setup the power mode correctly, a core's clock only slows down when it's not needed.
It will fire back up automatically when it's needed to run something. As long as you've disabled any throttling (basic power settings for a laptop), doing this "fix" can only have bad results.
- Refusing your processor the rest that it's designed to take could have a whole number of side effects.
* Excess heat... Over the lifetime of your laptop, excess heat can be fatal for your computer. You will begin to get more and more blue screens as it reaches critical temps and automatically dumps everything and powers down. If this happens too many times, it can even permanently damage gates in the cpu and memory when temps get over 200F. Laptops are generally not designed to handle the heat their hardware is capable of dissipating. This is why so many laptops need cooling pads.
* Excess power usage... This can overheat your power brick. If it gets too hot in can burn the insulation off of the coils in the transformer and short out. Most likely outcome is the smell of melting plastic and no power to your laptop. Over the lifetime of your laptop, excess power usage can also prematurely wear out your battery. Lion batteries have a limited number of cycles and each cycle they lose a little bit of their storage capacity. Long periods of high discharge rates combined with excess heat from a floored processor (that isn't using it's power saving) will most definitely result in the classic, "don't unplug my laptop, it will die immediately".