I'm sorry, but it's not clear to me what you don't understand, or what you're struggling with. I'm not being sarcastic, it's really hard to figure out what you are doing exactly.
If you don't fully understand the mechanism of the knots, be careful, because you might be doing the wrong thing, which is not good. I'm not sure whether this is the case or not, but you might be confused with which end is which. It does matter, and it's important. There is only one stopper knot, at the short end. The other end is the free-sliding end.
Try this: Follow exactly what the video says from the beginning to the end. Then, try to loosen the stopper knot a bit, and wiggle it down towards the noose knot, and tighten it again as close to it as you can. This should give you the end result you're looking for.