SIA-R24`<video>` element visual content has transcript

Accessibility requirements

This rule tests conformance of the following accessibility requirements:

This rule checks that prerecorded <video> elements have all audio and visual information available in a transcript.

This rule applies to every prerecorded <video> element that is visible where the video contains audio.

The visual information of each test target is available through a text transcript that is available either on the page or through a link. That text transcript is visible and included in the accessibility tree.

A "text transcript" in the context of this rule is defined in WCAG 2 as an alternative for time based media.

This rule makes the following assumptions:

A mechanism is available to start the video and the video element is not simply used to display the poster.
The language of each test target can be correctly determined, either programmatically or by analyzing the content, and sufficiently understood.

This rule has no known accessibility support concerns.