Which workouts have the side plank core move Cathe describes in her article

Hopefully you will still see this, even though you posted some time ago.

For sure, these are in To The Max and Legs and Glutes. Also, Body Max 2 and the RWH series have "balancing snow angels" in which you are doing a side plank with your hand on the floor and arm extended (but she provides a modification that you can have your forearm on the floor).
 

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