What the standard says
Where pauses in foreground audio are insufficient to allow audio descriptions to convey the sense of the video, extended audio description is provided for all prerecorded video content in synchronized media.
Where this one sits
This is a Level AAA criterion. Level AAA is not required by the European Accessibility Act or EN 301 549, and W3C itself does not recommend it as a site-wide target — so we have kept our commentary to the A and AA set rather than padding out pages we cannot improve on.
How A11ySignal checks it
manual
No automated rule can judge this criterion, and we will not pretend otherwise. A clean scan does not mean 1.2.7 passes — it means nothing we can measure fails. This one needs a person.