In this video I show how to dominate your opponent from the back position and then finish with an armbar.
There are many ways to successfully armbar your opponent from the back. In this video I show how to do it off of the T-Grip or the Kimura grip. This is a great starting armbar from the back for students that have not developed the proper hip movement to finish with some of the other variations.
I really like this variation because of the domination that the hand grip provides. It frees up your hips and allows you to transition slowly without losing control. If you notice in the video I stop and give Marty an opportunity to try to escape before I bring the leg over the head to finish. He cant turn in or turn away, just make sure to keep a good grip on that hand and lightly push away with the forearm on the face (dont get carried away contorting your body to add extra pressure to the head).
It is still essential to maintain a pocket on the back. This gives the space for you to easily move the leg out so your opponent can fall into that pocket. If you don't have the pocket it will be VERY difficult to get your hips out.
Once you pass the leg over the face you can bow your knees out to keep control on the head and on the hips (watch the video for reference) but as soon as you let go of the wrist to fall back and finish the armbar you MUST squeeze your knees to keep good domination.