One other point, among many about this series of videos, is that as he explains it, the Harbor freight meter he is using is measuring internal resistance of the battery in order to calculate "cold cranking amps", rather than putting the battery under starting load and measuring actual cranking amperage.
That may work okay if the electrolyte is standard sulfuric acid, the concentration is correct, the cells are filled, and the terminals have good contact, so the resistance is reasonably accurate.
But as soon as you change the electrolyte, its resistance changes. You have just changed the resistance of the solution, not necessarily "restored" a battery or somehow repaired a bad cell.
And his advice to spoon in wetted epsom salts (he actually spoons in dry salts at one point) with no attempt to measure ( a few cells he arbitrarily adds more to half way through his tests) is kind of like a kid making a mud pie, and pretending to be scientific about it.
Unlike other youtube epsom salt/lead acid battery conversion videos, this guy does not even empty out the old electrolyte first, or rinse with distilled water, he just spoons in odd amounts of epsom salts into old sulfuric acid electrolyte as the mood takes him.
Further on in the series this becomes an advertisement for a charger he builds (and apparently sells) with an open frame out of wood and sheetrock screws, a rectifier, a monster filter capacitor, and a wall timer, and a $2 multimeter from Harbor Freight with a bad battery (as he explains) giving false readings. His "Capacitative' charger has exposed terminals throughout, a ball of wiring, and exposed alligator clamps for the battery, which he points and will charge with an output of 130V.

After wading through the series, which begins with recommendations that people do what he does, his experiments produce poor results. Apparently, it was still worth putting up on youtube, so others could do the same thing.