I thought this was common knowledge about Andy?
You could play it with a mixed escape too. (And I think this might be how Andy is doing it more on that at the bottom). You could have a DSX motion primarily and on the 2nd and 10th notes do something to force a USX pick stroke:
You could try encouraging this with a pretty neutral pickslant, but attempting to rest stroke in a USX or DSX trajectory, something like this, where the notes are highlighted:
That might actually be a better way to at least “think about it” because as @Riffdiculous mentioned in your other technique critique (@doclearnstorock), you’re definitely aware of just when you need the different pick escape direction but you’re a little late getting to it. The rest strokes I indicated get you ready for it on the note before it’s needed.
I could be wrong but I think that’s what Troy will sometimes do in these patterns that require a mixed escape:
I could be misrepresenting him somewhat in terms of if he’s planning just when these rest strokes happen…but they definitely are happening, in both directions.
And that gentle/subtle change in slant is I think what Andy is doing too, if you watch around 5:55 in the video of the OP, when he really gets going.
His hand has that sort of gentle rocking motion (slightly pronotes/supinates).
To me that looks different from his more intentional DBX where his hand/wrist remain more neutral and don’t “turn” as much. Aside from the rotation he gets to help with the inside string changes on bigger skips, his hand almost looks like it’s just moving back and forth.
And that’s been my experience with this type of wrist based DBX. When it’s done correctly, it doesn’t even feel like we’re making a curved motion because it’s so subtle of an arc. It just “happens”.