Overly simplified how the 901 trans work. Well actually any manual transaxle.
It transfer power via the pressure plate to the clutch disc to the main shaft, which when it has a gear picked, then turns the similar gear on the 2nd shaft that turns the pinion gear which then turns the ring gear, which then turns the differential gears, and turns one tire to propel the car. I left out all the little detail parts that make it work, but that is the basics.
Only detail that changes is when you run a limited slip or Torque bias diff, then it can drive both wheels if the conditions are correct for it to do so.
The DVD is great at explaining all the various mechanical aspects of the 901 and how to make it work as well as you can as a DIYer.
BTW, Dr. why not offer it as a video format other than a DVD, I have not had one of those spinning disk things since my 2001 Mac Book Pro. The ones made out of titanium. We have to use them every now and again at work, we go back to the shelf, pull off a USB DVD player / writer and setup a pentagram a few candles, and start the process of firing it up. Only thing worse would be a tape based system.
BTW, if you think you can just rip it, and convert it to some other format. Cupomeat did a great job of protecting intellectual property. Not trying to steal said property just tried to get it to a format I could play in the shop. Pause and stop, and not have to run from the house to the shop every ten minutes and hope that a squirrel did not come along for me to go SQUIRREL and forget the details I just watched.