Began watching it today. Like the explanations so far.
One small correction for density discussion in chapter 2: 1000kg is not 450lb, but 2200lb (1000lb is 450kg, well, 453kg to be more precise). When you convert kg to lb you need to multiply by 2.2, not divide by 2.2. By the same logic, 4188kg is not 1900lb, but about 9200lb.
I had used that slide in DOPs classes for over a year before I realized the mistake - and in all that time, nobody ever caught it. Sadly, by the time I noticed, it was too late to change the DVD.