Well you know how to embed a Youtube video in your blog. But by default these embedded videos don’t play automatically. If you want the videos to play automatically when the page is loaded, well here is how to do it.
Copy paste the embed code for the video from youtube in your blog. Find the embed tag with the video URL which would be something like this
here http://www.youtube.com/v/LU8DDYz68kM is the video URL. Just replace the parameters right after the video url i.e., “&rel=1” with “&autoplay=1” so that the embed code now looks like
Now embed the video with the modified code in your blog and it would autoplay when the page is loaded.