I’m gonna call bullshit here. The difference in arm pose couldn’t be covered in any reasonable burst period.
The poses would be at least a few seconds apart which rules out anything in Apple's computational photography pipeline e.g. focus and dynamic range stacking. At least based on what they have communicated to date.
We know Google demonstrated an AI model that was capable of selecting human parts from multiple photos but that was a showcase feature not something quietly added.
Which is well under the 2 seconds computational photography clip.
Live Photos was not enabled and even still doesn't work like this.
Are those 3 poses she's doing, or did she have her hands clasped, then performed some gesture where she dropped her left arm then right arm?
The right definitely looks like a deliberate pose, at first glance the middle does too, but the left doesn't at all, it looks like a gesture. The splay of the hands among other things indicate this to me.
I think the middle isn't a pose either, just a transition. I think only the right is a pose, and it goes Right > Middle > Left in time. Her hand is splayed in the middle like it is in the left.
And the latency for taking a standard photo is not 2 seconds.
Live Photo means storing the video in the image file. Turning it off doesn’t mean the video is no longer used, just that it isn’t stored.