Hi Tom:
Re the knife used in these videos reminds me of the ones my dad used in
upholstery.  He copied an old Osborne one, making his own from discarded
Swedish steel metal cutting saw blades from a metal shop (I’m pretty sure
these were high carbon steel, not high speed steel).  These metal cutting
blades were about 1.5” by 24” and maybe 1/16”  thick and he would cut off a
length,  grind off the teeth and then make similar single bevel knives like
those shown in the video.  Watching these videos brought back memories of
him showing me how to work leather, button tuft diamond patterns, turn
corners...

  My dad taught me another important lesson: That you can learn something
useful from just about anybody if you are open to it and treat them with
respect, even a janitor (nothing against janitors, my mom was a cleaning
lady).
  Speaking of which, I just remembered the first time I chatted with the
janitor at the metal factory when I was a young dumb teen in a summer job.
  I innocently asked the old Polish man about the greenish colored numbers
tattooed on his forearm.  I didn’t really know anything about concentration
camps at the time.
Claudio