He correctly worked out the equivalent resistance for each of the three groups of resistors but then he should have treated the rest of the problem as a series circuit.
By my calculations, the left-hand group of four resistors will have 63.1V across them, the middle pair 49.7V, and the right-hand group 127.2 volts.
I'm a little puzzled as to why he decided to work out the total power the long way like this. He'd already worked out the overall resistance as the first part of the problem, so why not just use E^2/R, or do as you did and work out the current then get the power from I x E?
[This message has been edited by pauluk (edited 05-31-2006).]