Youtube videos are notorious for leaving out info or being inaccurate. The parts of a bicycle interact with each other, and videos often don't refer to or provide links to other information that may be related to the problem or procedure. Many people want to show off their tools or don't think about the realities faced by people who don't have or can't afford specialized tools. I would never suggest following a video by "regular people," as being able to do a procedure is not the same as being able to teach it. I found multiple errors and omissions in the first video in a Google search (I noted most of them): https://www.youtube.com/watch?v=aMSZ8Z8i-KY

I suggest in the future you consult sheldonbrown.com or parktool.com blog and use videos primarily for the purpose of seeing the procedure in practice.