Looks pretty simple after looking at it again. He has a few female headers alongside the atmega to get access to all the pins, so soldered right to the socket pins next to it, same for the tiny (except it looks like they are bunched together and probably wired to the tiny socket), he has the 6 pin programmer header connected to both of the chip's sockets (signals are VCC, MISO, MOSI, SCK, RESET, GND), he has a push button and pull up resistor for the reset on both chips, and he has 5V going in to the board, a filter cap, and a status LED probably straight from the 5V line.
Its more of a breakout board with female headers than like an avr development board or arduino board which often contain extra circuitry (like serial ports, linear regulators, etc)
Looks pretty simple after looking at it again. He has a few female headers alongside the atmega to get access to all the pins, so soldered right to the socket pins next to it, same for the tiny (except it looks like they are bunched together and probably wired to the tiny socket), he has the 6 pin programmer header connected to both of the chip's sockets (signals are VCC, MISO, MOSI, SCK, RESET, GND), he has a push button and pull up resistor for the reset on both chips, and he has 5V going in to the board, a filter cap, and a status LED probably straight from the 5V line.
Its more of a breakout board with female headers than like an avr development board or arduino board which often contain extra circuitry (like serial ports, linear regulators, etc)