This is a great butterfly breakdown explanation. Please mute that music in the background it's terribly distracting. You are excellent at explaining and to listen to so no need of the heavy music
The timing may be most important to me: head up first, breath in, then arms pulling. I've been doing arms pulling a bit earlier than head up breathing in, and struggle with bringing the arms above the water and get very exhausted after 12m. Will try this technique tomorrow and keep you guys updated with progress.