OK, this video is not very helpful, I just wanted to show everybody how to slide on the floor to initiate the knee bar from Down/Up. It's not an effective strategy, but it can come in handy when the opponent is gassed and try to escape your guard pulling: just slide to initiate the knee bar and win by surprise submission.
I only did it ONCE online, but it was epic! The opponent couldn't believe it, he messaged me to know HOW did I slide so fast to get the knee bar. That's why I made this video, sorry if it's a little boring...