How It's Made Ingine Pistons

I'm kind of amazed that the forging (1:30) is done by hand. The movement of the preheated, prulubed slugs into the press would seem to be very easily done by machine. I'm also a little surprised that the final sanding/smoothing at 4:15 is done by hand as well.

High heat to strengthen the metal then lower heat to stabilize it? That sounds kind of like annealing and tempering.