How does the through-diamond rolling-cue-ball one-rail two-to-1 kick system work?
The system is described in “VEPS GEMS – Part VI: One-Rail Kicks” (BD, June, 2010). Here’s a video demonstration, from Vol. IV of the Video Encyclopedia of Pool Shots (VEPS), with a complete explanation:
The following video shoes various visual ways to apply the 2-to-1 system:
Here’s another useful video, from Vol. III of the Billiard University (BU) Instructional video series:
The visual equal-distance mirror system is also based on the 2-to-1 system.