Here is the link for a clip of underswitch and overswitch drills (also called spearswitch and zipperswitch) from an Easy Freestyle Clinic in Charlotte, NC. The start of each sequence is the skate position, which is the ideal balance position on my horizontal axis for freestyle. My arms then move to position, pause, and drive to their target. The propulsion forward is generated fom my hip drive, not the pull. Position on axis is always maintained. This is the heart of "core swimming."
Learn more at www.heart2swim.com