I think of it as describing the movement pattern for just one mogul.
I have heard others use the "down then up" movement pattern to better explain mogul turns.
We come into the shoulder/rut, absorb (ie down movement),
ride over the crest, then extend (up) to maintain ski to snow contact
Contrast with a intermediate turn or wedge turn:
move up** to flatten the ski, and allow the tips to drop into the fall line
then move flex to manage the pressure as the skis are directed across the hill.
up** not trying to propose old school up movements for initiation
but we do want to flatten the ski, so whatever movements facilitate that: up / forward / foragonal. (not down in any case)
As TheRusty points out:
This can be especially true if you get strict about considering the start of a turn to be when the ski is flat on the snow.
If you consider the start of the turn to be when the ski stops turning more in the other direction, then the section of the clip you reference
(1:117-1:25) does indeed show turns that start with a retraction (in this case an "absorption") move. If you consider the turn to start at edge
change, then it starts with an extension move.
In mogul skiing it is (at least to me) more natural to think of the turn as starting going into the mogul, ie down then up
when you slide into that first mogul mogul field, the first move would typically be "down". especially if your are zipperlining.