@sphirst I dunno. I don't know python, but it is not like you will break anything trying it.
I just thought you should know that there are several discussions active right now on the topic of shutdown scripts. Most of my work recently has been related to the Mausberry circuit, a little PCB that goes on the USB port and hooks into GPIO to trigger safe shutdown. You can do something similar without the circuit, but the Mausberry adds the ability to truly cut power.
I did not look at the video you linked above, but you might also find a little software package called GPIOnext interesting. This is the evolution of GPIOneer, a GPIO button handler/driver created by mholgatem. I use GPIOneer, but I will be replacing/upgrading. My buttons that use it include volume control as well as safe shutdown.