There's a series of videos by the same YouTuber going over the process in detail. If you're squeamish, I'm sorry in advance . .
The lesson I learned . . .have a very very sharp knife, mine wasn't and the result wasn't pretty.
Thankfully I had a friend helping me that has experience so he finished the kill. I did the majority of the cleaning and he only stepped in when I got too close to 'things you don't want spoiling the meat'.
Did I enjoy it? No! Would I do it again if necessary? Another time or two with help, I'm sure I could do it on my own.
It helped that I was fed up with the rooster attacking me and I wanted it done, so the emotion was mostly removed the situation.