In this video I show a very simple stacking defense for the armbar. There are multiple different ways to defend but I enjoy showing this to beginners because it is a defense that you can use when you didn’t see the setup for the armbar coming and your opponent already has their angle and their hips out.
Make sure when you stack your opponent up you get your knee as close as possible to your opponents ear and you post your back leg at an angle so that your knee is against your opponents lower back. This should set you up to have good base. Make sure to keep that shoulder pressure DOWN on your opponents face and make the position very uncomfortable for him/her.
Under no circumstances are you to lift that shoulder pressure off of your opponent. As soon as you do you will get swept or pulled into another position that you dont want (like an omoplata). Make sure that all of your weight is on one side of your opponent and with the exception of that shoulder pressure down none of your body weight should be put on to your opponent (especially his/her hips).
If you have problems clearing your arm from the armbar be patient. It can take a long time to get that arm out. In the meantime keep that shoulder heavy, make little bumps and watch your base.
After you clear the arm that is being armbared make sure to maintain that pressure on your opponent. He/she is going to be looking for an out (again typically the Omoplata) and you still need to clear that second arm. After you clear the second arm make sure to rotate to the opposite side of your opponent and turn their hips away. This will set you up for success in the next position.
Thanks for watching!