What is an auto jerk rig system?

What is an auto jerk rig system?

This system moves a dozen decoys and will out perform a spread of dozens of decoys that do not move. The Auto Jerk System will create an effective natural decoy motion without pulling on a string. It puts ripple and non-stop motion in your spread. It is portable and can be set up in ten minutes.

How do you make a jerk cord?

https://www.youtube.com/watch?v=tJMdTVvl7Zs