video-poster-text-alternative-present
<video> poster must have a text alternative
Checks that <video> elements with a poster image provide a text alternative (accessible name).
Applies to. Applies to <video> elements that: 1) have a non-empty poster attribute, AND 2) are exposed to assistive technologies (per engine eligibility checks). Elements otherwise hidden from the accessibility tree remain applicable if they are tabbable or referenced by IDREF relationships (per eligibility checks). Videos with role="presentation" or role="none" are excluded only when they are not focusable.
Expectation. Each applicable <video> element provides a text alternative for the poster image, via:
- an accessible name (aria-label / aria-labelledby / title).
Between-tag fallback content inside <video> is NOT accepted: it is only rendered by browsers that don't support <video>, so it is not reliably exposed to assistive technologies in practice. <video> is also not a labelable element, so native <label for="..."> associations are not accepted either.
Examples
<video poster="poster.png" aria-label="Product demo"></video>
`aria-label` names the video element that carries the poster image.
<video poster="poster.png"></video>
No accessible name and no fallback; a poster attribute alone isn't a text alternative.