TL;DR:
There're lecture notes about a very simple reduction from "maximum flow with edge demands problem to the maximum flow problem. But I can't get the new capacities at the picture:
E.g., look at the diagonal: 15 - 0 = 14 (?). From my point of view there're a lot of off-by-one errors.
Those are just typos, as you can confirm by reading the general construction on the previous page ("Intuitively, we construct $G'$ by ...") and applying it to the flow network on the left. Yes, there are multiple off-by-one errors. It happens. Pobody's nerfect.
Incidentally, you might want to read the latest version of his notes, available from http://web.engr.illinois.edu/~jeffe/teaching/algorithms/, rather than the 2009 version you're reading right now (though this particular typo is still present).
