Oh god, not this again.
Youtube run: Beginners can only take a few steps, often they lose balance doing anything else.
Relax run: Looks fucking horrible, you tend to lose balance fairly easily because your don't hold chest/lumbar
Custom run: The opener doesn't really matter, some of us use the Youtube run opener to start, what's custom is our arm style, how we use our pecs, the way we use our legs, ankles, we think more about what we do. Many of us take a good couple of months before we find our true run that looks good and that's fun for us to do.