That Vid is a bit dated, but some shortcuts:
- skip kkmulticopter.com -- LazyZero's kkmulticopter flash tool is hosted here:
http://lazyzero.de/en/modellbau/kkmulticopterflashtool
The tool is about 1/3 of the way down the screen, the driver is about 2/3 the way down.
- you are using the USBASP, but your board is a "kk2.1 and kk2.1.5"
- the latest firmware is not Steveis's 1.9 -- don't trust the order in the list to get you the "latest"
- the blue "i" button next to the firmware will take you to a official page/blog/thread for the selected ROM.
- you will need the 6 pin header. The 8 pin (more standard) has all the right signals, but not to the right pins. if you've built adapters before, it's trivial to fix. if you haven't . . . 8 to 6 pin adapters they are sold online.
- If you plug it in backwards . . . nothing happens. It won't power up, but noting will be damaged. If you plug it in the right way around, the USBASP will self-power the board.