So I came across this page today and it's working wonders. It took a page on my blog from 3mb to around 600kb in total size.
http://www.labnol.org/internet/light...-embeds/27941/
All you have to do is pretty much write this in the footer & upload the file from the page above.
I suggest trying it on a page with 2 or more youtube videos and you will definitely see a change not only in the loading times of your pages but also a bit of a increase in your pagespeed/yslow scores on webpagetest.org and both of these are always a plus!
Code:
<script src="http://site.com/youtube.js"></script>