Unfortunately Harris is a moron who doesn't understand pretty much anything outside of his narrow field of expertise, and Free Will is a philosophical, not a scientific concept. Added together, what we get from Harris is a Dunning-Kruger bordering on Creutzfeldt-Jakob.
Even worse, he interprets Libet and Haynes to disprove free will when neither does, and that in a most unsophisticated "scientistist" sense of the term.
Free will does not exist. It is man made concept, which shows nothing else but arrogance of human kind to think that they are inseparable of environmental influence. Everything in Universe, including thought is directly influenced and shaped by environment and cannot exist out of this influence.
Same as concept of consciousness and awareness is nothing more but very complex, advanced cognitive function in the brain. If your brain gets badly damaged, you can lose this ability.
Also Harris, in this video did not say that free will is a scientific concept. He actually defends and proves that it is not, and proves that it is nothing more but illusion. Nothing more but false philosophical concept.