Christopher Sommer a.k.a Coach Sommer is a gymnastic coach from the USA who got particularly famous for his articles on planches and front levers originally published by DragonDoor.com. He is also the the author of many books dedicated to gymnastic training which can be found on the website: http://www.gymnasticbodies.com
The video below is a podcast by the guys from Barbell Shrugged who had Christopher Sommer on the show. The video is 43 minutes long and touches on gymnastic training and CrossFit.
Pay special attention to what Coach Sommer has to say about kipping pull-ups and his idea about the “sweet spot” – combination of bodyweight gymnastic drills and weightlifting.