Updated
Add &mute=1
to the end of your url.
Your new code would be:
<iframe src="https://www.youtube.com/embed/uNRGWVJ10gQ?rel=0&autoplay=1&mute=1" width="560" height="315" frameborder="0" allowfullscreen></iframe>
Updated
Add &mute=1
to the end of your url.
Your new code would be:
<iframe src="https://www.youtube.com/embed/uNRGWVJ10gQ?rel=0&autoplay=1&mute=1" width="560" height="315" frameborder="0" allowfullscreen></iframe>