man, if that video isn't a perfect sales tool for a plaster finish wall, I don't know what is. If they level 5 everything, why don't they just go to a skim coat plaster.
With the level 5, you still have sanding, not with plaster.
then, as a bonus with plaster, you don't even have to paint if you don't want to. You can use colored plaster and be done with the application of the plaster.
It is really kind of funny that the more people try to make drywall look good, the closer they get to the product it was created to replace and actually end up spending more money than the product it is used to replace.