Audio Control

Understanding WCAG2.0

Uses a mechanism that pauses or stops the sound when the sound on the web page is automatically reproduced and lasts longer than 3 seconds or a mechanism that can adjust the volume level without affecting the volume level of the entire system it can.

By the way, YouTube is automatic playback. For the visually impaired, there is also the aspect that automatic regeneration is appreciative (= you get the flow of getting information just by stepping on the link, and there is also the understanding that YouTube is that kind of thing). The convenience of this automatic playing may be possible other than YouTube, but please be careful on ordinary web pages.

Principle Perceivable Information and user interface components must be presentable to users in ways they can perceive.
Guideline Distinguishable Make it easier for users to see and hear content including separating foreground from background.
Criterion Audio Control
(1.4.2 A)
Uses a mechanism that pauses or stops the sound when the sound on the web page is automatically reproduced and lasts longer than 3 seconds or a mechanism that can adjust the volume level without affecting the volume level of the entire system it can.

URL of Techniques for WCAG 2.0