I'm reminded of part of (my family) history where I discovered that my grandfather had worked on the UPC system.

The original "test blanks" for UPCs were steel plates with machined cuts in them, photoreduced down to small sizes for testing.

A good channel overall. Some things are better, some other worse but for instance, his explanation of the Bayes theorem is on par with the one from 3blue1brown

“a guy” aka Veritasium, the channel with 17M subs