August 2018 I didn't find a working example on the iframe implementation. Other questions were related to Chrome only, which gave it away a little.
You'll have to mute sound mute=1
in order to autoplay on Chrome. FF and IE seem to be working just fine using autoplay=1
as parameter.
<iframe src="//www.youtube.com/embed/{{YOUTUBE-ID}}?autoplay=1&mute=1" name="youtube embed" allow="autoplay; encrypted-media" allowfullscreen></iframe>