Hmm, not so sure it is a fake. When you say that she focuses on the cam, and doesn't move her head while moving her body, just remember that she tries to look 'seductive' for her boyfriend (I suppose).
Besides, what do they have to gain by making such a webcam movie? Really? I can't see both females getting anything but a 'bad' rep from this...
But we'll never know, won't we?