Here they actually talk about knee and foot angle (in the begining of the film) and about correcting it. This is film number two, there should ba a number 1 and maybe more.

http://www.youtube.com/watch?v=umUSVWf5604

Several others also as you can see. Much more info than you need and confusing, but I think in your case it may be worth it reading several peopels opinion, watch some films and then go back to what makes sense for you.