LayerSlider, youtube video wont autoplay

Hello everyone,

I tried to make a slide with LayerSlider and in this slide i added a youtube video. Here’s the link of the video that i used : <iframe width=”640″ height=”360″ src=”https://www.youtube.com/v/llAa3CTdNEw?version list=PL0pVvHBGUrQghkWhl_OA-AlZ6gw85Znbo&controls=0&autoplay=1&loop=1&showinfo=0″ frameborder=”0″ allowfullscreen></iframe>

With this link, we can see that the video autoplays but when i click on preview it does not work.
Does anyone have an idea to fix this ?
Thanks in advance for your help