There were three basic systems discussed. The first was roughly the standard 1-cushion double-the-diamond system, but it includes the cases when the target is on a cushion and not in the pocket and the case when the cue ball is in the "open table." The system as presented changes the spin on the cue ball depending on how far across the table it starts.
A second system is the plus-2 (end rail/side rail/side rail) including the numbering needed for extension to the (second) short rail as the third rail.
The third system is the corner-5 primarily for hitting a target on or near the third cushion with a very brief explanation of an extension to get to targets a small distance from the third cushion.
As for your confusion, it's understandable. Most people don't understand that there are lots of diamond systems. If they want to see lots more systems, they may want to consider getting the books by Bob Byrne and Walt Harris.