We are used to see Arduino as standardized board that has special layout of pin sockets. We don’t say they are very expensive, but in some cases we don’t want features of board. For instance maybe we want Arduino to serve only as analog input only for Raspberry Pi. Arduino is great for its libraries and is good choice for fast implementation. So Wolf Paulus minimized Arduino to AVR microcontroller itself.
He says that throw away everything except Aarduino which is AVR Atmega168 (or Atmega328). It has internal clock which can be run at 8MHz. Attach power to pin 7 and 8 and you have it. Obviously you don’t need a booloader for such Arduino, so it has to be added as different hardware in Arduino IDE in order not to try send firmware. Instead chip needs to be programmed using ISP programmer. Anyway nothing especially new here – just another way of using Arduino.