Every visible extra has a job

Background people who move together, or stand with nothing to do, give a shot away fast.

The rule [official guidance]:

• Each visible extra has one ordinary task, at their own tempo and in their own direction. No two extras move together.

• A group reacts as a ripple that runs through it, never all at once.

• Write them in a BACKGROUND line per shot, never as "people in the background": "BACKGROUND: behind her, a waiter stacks chairs one at a time; at the far table a man folds his newspaper, then checks his watch; a boy carries a crate across the frame, right to left."

• A distant crowd too small to read as people counts as one of the place's live motions, with its cause, direction and rate.

Check it on frames exported every 0.5 s, watching the background, and confirm by stepping frame by frame: two extras who start, stop or turn on the same frame fail. The fix is one task each, never a retouch.

Why: in Higgsfield's own Seedance 2.5 short film, guards who moved in sync were fixed by giving each one a separate reaction. Their working rule is that every extra needs a job.

Sources

• Higgsfield, "How I Make Realistic AI Short Films Using Seedance 2.5" (video).