Wrench, I would suspect that he used a rougher reamer and no finish. At least, that is what it looks like to me. I don't see the spiral you get with packed chips when you withdraw the reamer. Could also just be a super dull reamer. That said, it's hard to judge in the video.One turn (assuming the headspace was right and 16tpi) would be .062"
If your smith chucks it up and takes a cut, he can see if it cleaned up.....then index your marks.
If your bedding was beyond the shank, it may alter the appearance up there too.
It would take a pretty good chip weld to get that many rings. That is an impressive mess.
Just my 2 cents on root cause. Correction has been well covered by you and others.
Jeremy