When the page loads, the YouTube video should play the video without sound (unmuted), but I could not find a proper way to fix this.
var video = document.getElementsByClassName("embed-responsive-item");
if(video == video.mute()){
video == video.unmute();
} else {
video == video.unmute();
}<div class="embed-responsive embed-responsive-16by9">
<iframe class="embed-responsive-item" src="https://www.youtube.com/embed/KKp9g8fTBDQ?autoplay=1"></iframe>
</div>