Spin-under to the back from closed guard
Here's the next technique from Eduardo de Lima.
I hope to get some people saying that this is just too advanced and would never work or that it's a gimmick (as has been said about a lot of the awesome stuff I've put up), because then it's even funnier when others try it out and find that it works really well.
This is a creative way to take the back when someone stands in your closed guard. You may already be familiar with an x-guard move that is just like this, in which case you'll see how well this can work. If you've never tried a move like this before, you'll probably think this is impossible.
In either case, here it is:
Start with them kneeling in your closed guard.
As they stand, twist your upper body. With your right hand, reach under yourself for their opposite foot. Reach to the inside of their opposite knee with your left hand.
From the opposite angle, you can see how you put the back of your right hand on the outside of their ankle and hook under their knee with your left.
Use your arms to keep twisting your body under him...
...then open your guard and use the torque of your arms to spin under him, pivoting on your shoulders.
Bring your knees in between his legs and put them behind his knees.
Chop out the back of his legs with your knees as you pull his ankles so he falls forward.
Once he's fallen to all fours, keep ahold of his ankles with your feet hooks behind his so he can't stand up again or turn into you.
Grab his belt and pull yourself up until you can grab the back of his collar too, then jump up and put your hooks in to take the back.