This is an update to my previous version of the 80x25 tv video output library for Arduino. Grant Searle has updated his video processor code (upon which this is based), to support 4 bit mode. This reduces the number of I/O pins required from 10 down to 6 (4 bits and 2 control lines). See his page for further information on that.
80x25 TV Video Output Library for Arduino library, and extract it into the libraries folder inside you arduino projects folder. The choice of the 6 pins is up to you, here is how it is wired in the code examples in the library.