Facebook and Skype have teamed up for video chat right there in your favorite social network. Skype video calling is one of the new features in Facebook Chat -- and you can try it out right now at facebook.com/videocalling.
To make a call, simply click on the new Call icon at the top of a friend's profile, in between the current Message and Poke buttons, or click the video icon in the Chat window.
You need to download a plugin to get started. When you call a friend who hasn't got the plugin yet, they will be prompted to download it, and you can be chatting face-to-face inside a few seconds.
The advantage over Skype itself is that you can simply call your friends, instead of having to know their Skype username to find them. It also means all 750 million Facebook users can video call, as opposed to the mere 170 million users of Skype.Source