How to debone a chicken without cutting it into pieces (like this video)

Hello everyone. First of all, English is not my first language, so I apologize in advance for any mistakes. My favorite recipe is roasted chicken, and I usually cook it with the bones included. However, after watching this video on YouTube, I would LOVE to be able to debone the chicken like this before cooking it. In the video, you can see how it's done, but it’s very fast, and I can’t manage to do it. I also don’t know if this is a technique with a specific name. Any suggestions are welcome. Thank you in advance! https://www.youtube.com/watch?v=hrhES-cFa50 submitted by /u/Anonymous_Wal