In order for a document to be accessible, all multimedia (such as audio or video clips) must be tagged. 

If the content is only for decoration, mark it as an artifact using the Reading Order tool. Open the Reading Order tool on the Accessibility panel. Use the cursor to draw a rectangle around the decorative content (or click the number or abbreviated tag type if the decorative content is already tagged). Click the "Background/Artifact" button on the Reading Order dialog box to tag the item as an artifact and remove it from the tags tree.

If the content is not just used for decoration, use the Reading Order tool to tag the content with the appropriate tag. Learn more about tagging with the Reading Order tool.

Captions or audio descriptions may need to be added for some multimedia. Please refer to WebAIM for more information about captions and audio descriptions.

WCAG requirements: 1.1.1 Non-text Content1.2.1 Audio- only and Video- only (Prerecorded), 1.2.2 Captions (Prerecorded), 1.2.3 Audio Description or Media Alternative (Prerecorded), 1.2.5 Audio Description (Prerecorded)