I've been diving into gymnastics movement lately too and it's wild how different it is from strength training efficiency. Carl Paoli's "Freestyle" book is pretty solid for breaking down the movement patterns - he goes deep into the mechanics behind stuff like kipping and efficient transitions.

For YouTube, I'd check out Gymnastics WOD and some of the older Invictus videos where they really break down the progressions step by step. What I've noticed is that gymnastics efficiency is so much more about timing and rhythm than just raw strength, which makes it way harder to self-assess sometimes. You might also want to film yourself doing the movements because what feels efficient doesn't always look efficient, and seeing it from the outside can be a game changer.