if you want to set a youtube video to start playing automatically when to page loads, all you have to do is put ?autoplay=1 at the end of the url

for example, lets say when you get the embed code it looks like this:

<iframe width="425" height="349" src="http://www.youtube.com/embed/yH2yfwwxgpk" frameborder="0" allowfullscreen></iframe>

so all you have to do is make it look like this:

<iframe width="425" height="349" src="http://www.youtube.com/embed/yH2yfwwxgpk?autoplay=1" frameborder="0" allowfullscreen></iframe>


the old code you have to put a &autoplay=1 at the end of the url, like this:

<object width="425" height="349"><param name="movie" value="http://www.youtube.com/v/yH2yfwwxgpk?version=3&amp;hl=en_US&autoplay=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/yH2yfwwxgpk?version=3&amp;hl=en_US&autoplay=1" type="application/x-shockwave-flash" width="425" height="349" allowscriptaccess="always" allowfullscreen="true"></embed></object>