Unforunately just because Ulisses has an amazing physique doesn't mean he knows much about the biomechanics or muscle recruitment of lifting.
"Bipolar surface electrodes placed on the bellies of the v. lateralis and v. medialis and on the lateral and medial portions of the rectus femoris revealed no significant differences in electrical activity for any muscle due to changes in foot position during the squat."
http://journals.lww.com/nsca-jscr/Abstract/1995/08000/Effect_of_Foot_Position_on_the_Electromyographical.11.aspx
Journal of Strength and Conditioning research. Can't get much better than that. Beleive what you want though; whatever works for you, works for you.