I think part of this is a misunderstanding about what Becky's trying to work on. She never wants to jump them. Jumping them is not ever going to be the goal. She'll never canter over them. Prior to beginning this, her horse had been locking in the stifle, and she's walking him over high cavaletti to strengthen and increase his flexibility in the back.
You know, if you do hunter/jumpers and event horses, you think of everything in terms of working towards jumping. (To the guy with a hammer, everything looks like a nail!)