You can't accurately draw a human face - heck, any part of a human body - without knowing about how the underlying bones and muscles contribute to structure. And while disecting is by far the best thing you can do to improve your knowledge in these two fields, we don't all have the ability to do such things. So this video is the next best alternative.
Watch the tutorial to learn about the composition of the human face - the bones, muscles, and how and where the face curves upwards and inwards. This is a great anatomy lesson for any artist looking to represent a face more realistically.