Well, first for YouTube, oEmbed is built into WordPress and it takes care of that. So I'd get rid of the other plugin using those shortcodes, since you don't need it. Just [embed]http://youtu.be/iWiX8IUw36c[/embed] will work, no plugins needed.
Second, SFC processes shortcodes. So if the other plugin was capable of processing the shortcode on the admin side of things, then the shortcode would be processed into the embed code, SFC would pick it up and convert it into the proper video meta tags, and your shared post on Facebook would then actually have the video in it.
So, basically whatever shortcode plugin you're using that creates that shortcode isn't quite doing it right. Use embed instead. It's easier and it always works.