To present a YouTube embed video with sound muted with HTML, we set the mute
query parameter to 1.
For instance, we write
<iframe
src="https://www.youtube.com/embed/uNRGWVJ10gQ?rel=0&autoplay=1&mute=1"
width="560"
height="315"
frameborder="0"
allowfullscreen
></iframe>
to set the mute
query parameter to 1 in the video URL to mute the video embedded with the iframe.