When a boy, there was an unwritten law that you didn't kick when getting into a fight, it was an 'unmanly' thing to do, and if you did kick, even if you were to win a fight that way, there would likely be some ridicule, and the victory would pretty much get discounted among your peers. It could mean more fights! Plainly, people didn't use their legs. Around high school era that started to change, about the time that martial arts places started to open up, I think that there was a connection. Perhaps movies made an impact as well. Kicking became more prevalent. Still to this day it is kind of imprinted when I see someone kicking, like in that earlier video. The first reaction is wow, he kicked!