The most important thing you need to do when embedding youtube video on your site is disable the “realted content” that appears at the end of the video.
What can be more stupid than showing your customers who else has a video on this subject and help him go somewhere else?
All you need to do is add &rel=0 at the end of the URL and that’s it.
I have seen that on the bionase page. Before adding this parameter, at the end of the video all their competitors showed up to say HI. Now they are gone.
Youtube has some more parameters you can use when you embed videos. loop, rel, autoplay and showsearch look pretty useful to me.