With experience, I noticed most of people who say that they follow exactly the steps given in the tuto are following some things, like relaxing shoulders and pecs, it is the most common. Don't forget to read the description under the video too, I explain that I holded my abs.

In any case, that tuto isn't there to make you insta runner, that doesn't exists and replicate moves without understand them is the best way to stuck. It is a lot better to try by yourself and find your ways to continue your moves.