I like the author's dedication to his subject. If someone is going to pay $500 for coffee that has come out of a money's butt, he should be getting the real deal.
My observations concur with PlasmaGryphon. In most cases the preferred method of manually charging devices is with a hand-cranked, clockwork mechanism. Hand-cranked generators without clockwork come in second, but most people like small bursts of hard work rather than easier but tedious work.
A stride is the distance between paw prints of the same foot, so you would only have to look six feet or so for the next print. On the other hand, tracking a cheetah would generally be unadvisable.
My great aunt did not change a thing in her living room from the sixties until she died in 2005. Not quite 70 years, but period treasures none the less.
Trevor Baylis has worked on both. http://en.wikipedia.org/wiki/Trevor_Baylis#Invention