Answers for "youtube autoplay attribute"

iframe autoplay

<!-- 
first add ?autoplay=1 to your video url
then add allow='autoplay' attribute to your iframe element
-->
<iframe src="https://www.youtube.com/embed/dQw4w9WgXcQ?autoplay=1" allow='autoplay'></iframe>

html5 iframe youtube loop

<iframe class="embed-responsive-item"id="ytplayer" type="text/html" width="640" height="360" src="https://www.youtube.com/embed/M7lc1UVf-VE?&autoplay=1&loop=1&rel=0&showinfo=0&color=white&iv_load_policy=3&playlist=M7lc1UVf-VE"
      frameborder="0" allowfullscreen></iframe>