@Commukazi I've never had an issue, but then again I learnt it without the knee in the middle. The way I learnt, you almost use your inner thigh on the other persons hip. The idea is just get the other person's weight moving enough that the basic scissor motion is enough to push them over, along with the pressure from your upper body. I don't think he explained it particularly well in that video, but it's something that's hard to explain without doing

Nice vid, but I have a question: Just how effective and practical can this move really be in a match? He was taking into account that the other guy would push back, but how often would he actually get that far off the ground pushing with just one arm AND manage to shove the knee in at the same time?