This page has four video lectures produced by Duncan Mara on Simplified Sewerage.
The first three describe the theory behind the design methodology while the last described the application.
There is a fifth video which is taken from a documentary and called Return of the Drain Gang which shows a community in Pakistan transforming their living conditions by building themselves a simplified sewerage network.
These lectures are taken from Duncan's web pages at the Univertity of Leeds: Simplified Sewerage, Duncan Mara, University of Leeds