If this is the kind of stuff peddled by this book, I'd avoid it. There are many problems with over-simplifying aerodynamics, as the ATPL exams regularly reveal. The 'molecules travelling further' bit is one obvious area where conventional simplified aerodynamics break down in the face of fairly casual scrutiny.
As for engine failure, it is indeed true that the yaw initially will be toward the failed engine (OSOT, my aircraft will yaw left if either No1 or No2 fails!). What happens thereafter depends on how many engines you have, whether you are considering a 'stop' or 'go' situation, and whether reverse thrust is used. Nevertheless, the aircraft will always tend to yaw towards a crosswind, as you would expect.
Scroggs