an earth rod directly into the earth will be way different than same rod being encased in concrete and inserted into the ground. i am not suggesting earth rod for bonding purposes, its there to provide additional electrical paths for the grounding system. the MH video showed three earth rods many feet apart providing ~20 ohms back to service. this is a safety benefit for a few $$ in some earth rods.
And the benefit of getting the resistance down to 20 ohms is supposed to do what? How would we be able to permanently guarantee any low resistance? This has been discussed here ad nauseum for a long time- you may want to really re-think your position on rods. Also, think hard about concrete.......