Also, when Sensei is showing nuances of foot position, he hooks the hem in his belt
The following was taken from the Bugei Trading Co. online catalog. These guys seem to be pretty hardcore when it comes to samurai history.
"Hakama are the trousers that the samurai wore. They were the normal wear and not designed to hide the feet or give the illusion of floating. In fact the hakama was tucked up through the belt when confrontation was imminent, just as the sleeves of the kimono were tied back with a tasuki. There were many types and syles that came in numerous colors and designs. The samurai were fond of vertical stripes as well as other patterened designs..."