The video starts with some exercise for point number 3 Five Points Point 1 5:17 Step in positively, quickly and aggressively with the lead foot and use this step in to sort of charge the movement of your rear right kneeing leg. Point 2 6:07 Raise your hands a little and pull them down as you knee. This counters the movement of your centre of gravity, preventing your torso from being thrown backwards and moves your weight behind your knee. I thought that my dojo-mate were imagining holding the head of their opponent into their knee, which is what it looks like, and may also be good to do in a street fight. Grappling, grasping like tha is not allowed in karate. Point 3 8:28 Get a pelvic thrust, and movement of the weight of your torso, going behind your knee. That is the point of the exercises at the beginning of the video and the major point of this video as a whole. Point 4 10:43 Get up on your toes on your axis (standing) foot as you throw your knee to throw it as far as you possibly can. For that you need (in addition to strong calves and flexible Achilles tendons) upper thigh flexibility. Point 5 12:24 Move back to an proper (orthodox) stance to make counter attack less likely. If you have used your the downward movement of hands (point 2) to keep your body from falling one way or the other, then you should be able to do this.