How can I do face tracking on an AR Drone?

  ar.drone, face-recognition, node.js, opencv, windows

I searched the Internet for an eternity now and couldn’t find an answer.

The result should look similar to this:

They track his face and fly in this direction. Shouldn’t be that hard but I can’t figure out how they recognize his face.
Many research papers explain how face tracking works but there is never an API or Code.
I mean I could try to code my own but I have neither the skills nor the time to do that so I hope someone here knows something the Internet doesn’t.

Source: Windows Questions