Hi,

You can use the code like this on "Text" editor tab when you edit a post:

\
<iframe width="560" height="315" src="http://www.youtube.com/embed/GRonxog5mbw?autoplay=1&loop=1" frameborder="0" allowfullscreen=""></iframe>

For youtube video autoplay, loop.

Note this code after the src of the code above.

\
?autoplay=1&loop=1

You should change only video youtube ID 

\
GRonxog5mbw

on the above code to your video youtube ID. See how to find video youtube ID here

For mute video, you need to use more javascript because by default Youtube doesn't support this feature. The javascript is not take short time to do, so we don't provide support for this.

Best Regards,

PenciDesign