Yes, I actually do have a whole series of lesson plans in my brain - and often a written outline in my bag, in case I forget anything. You can read about it after the video. And you just thought I made this shit up as I went along. Well, fooled you, didn't I!
This video gives a good demonstration of how your legs should be working in the "Collect the Arm" turnover. You can see an explanation of it and a good illustration of the upper body portion in this post.
Often the turnover doesn't work, though, because people get the legs wrong. Notice that the player on bottom has one leg on the INSIDE and he LIFTS with that leg. His other leg is sweeping. So, you lift and sweep.
When you roll, you want to roll in the direction of the arm you have collected, that way, they can't put an arm out to stop you.
So ... what is being lethal on the mat about? It means there not being any position where your opponent feels safe. As any of the students in my class at Gompers Middle School can tell you, lethal means that you are dangerous to people.
This turnover is one position you could be - on your back with your opponent on top, but not so tight that you can't get one leg in to lift and turn.
Incidentally, that is one of the things people ask all of the time that drives me nuts,
"Sensei, I can't get my leg in to hook his leg from here."
"Well, then, MOVE, damn it!"
What is another position you could be in? You could be on top of your opponent, who is in a turtle position (on his hands and knees, elbows bent and head tucked in). You could be the one in the turtle position. Your opponent could have just thrown you and be still standing. You could have just thrown your opponent and be still standing. Your opponent could be flat on his stomach. You could be flat on your stomach.
If you want to be lethal on the mat, you need an attack from every one of those positions. So, over a couple of days, I will teach an attack from each position. Other times, I will be more specific and teach an arm bar from each position. It takes me more than one day because there really is not time to teach and practice a move from six or eight different positions, and do all of them right and left sided.
Do I really have an arm bar from every position? Yes.