How can I autoplay a video using the new embed code style for Youtube?

Just put "?autoplay=1" in the url the video will autoload.

So your url would be: http://www.youtube.com/embed/JW5meKfy3fY?autoplay=1

In case you wanna disable autoplay, just make 1 to 0 as ?autoplay=0

Actually, you will have to use the "?" instead of "&" for your first parameter only. If you use more than one parameter, you will then have to add "&" to the chain.

For instance, if you want to add autoplay and closed captioning, you will have to add this portion to your embedded video URL: ?autoplay=1&cc_load_policy=1.

It would look like this:

<iframe width="420" height="315" src="http://www.youtube.com/embed/
oHg5SJYRHA0?autoplay=1&cc_load_policy=1" frameborder="0"
allowfullscreen></iframe>

You need to add an extra parameter, alongside the autoplay=1

allow="autoplay"

making it:

<iframe src="your-video-url?rel=0&amp;controls=0&amp;showinfo=0&amp;autoplay=1" frameborder="0" allow="autoplay; encrypted-media"></iframe>