Ok, here are a few truths.
I watched the video. He begins with two statements in order to convince you that there is indeed something wrong with the so called antiquated practice of chambering barrels using conventional methods.
The first is that description of a barrel’s ID. If he has taken the time to section a barrel and ascertain the true nature of the run out in the ID of every barrel, he would see that the barrel’s ID is not bowed like a banana.
The second are the absurd tolerance’s he describes in the explaining of throat being off center with the chamber and how that affects accuracy. .001 to .005 of an inch of throat miss alignment in a finished chamber? Good grief, if I have the lands and grooves of the lead and throat running out more than .0003 with the rest of the chamber when I am finished, I start looking for the cause.
True, the steps involved in the entire operation of chambering is predicated on getting all machining operations truly straight with the throat. If your procedures are producing numbers over .001 inch, you need to review your setup and ascertain why.
Any Gunsmith doing extreme accuracy chambering can say the same thing. Since there are Gunsmiths who do indeed use CNC machines with excellent results, perhaps the cause of failure should be anylized.
My guess is the way they are doing barrels on their CNC machines is not producing the kind of accuracy in machining that is required for extreme accuracy. Since their production needs mandates the use of this equipment, they had to come up with something to make it all line up.
Which get us back to a solution in search of a problem. Rather than over complicating the machining operations required in establishing chambers, threads, and tenon shoulders that are indeed truly straight with the throat, why not figure out why your procedures are producing unsatisfactory results.