Henry Cooper's book was the first boxing book I ever read as well, followed closely by Floyd Patterson's.
There is a lot to be learned by watching tapes. That drop shift move seemed like suicide to me until I saw Benny Leonard do it on tape. Slo-motion is the greatest invention...I've watched whole fights on slo-motion, some of them (McGirt/Brown, Toney/Nunn to name two) a dozen or more times.
Damn, I need a hobby.