The Trap Guard is a great tool to have in your game, especially if you don't like playing traditional closed guard. It keeps you safe (even from punches) and will set up a ton of attacks and sweeps.
In part one of the series, Professor Steve covers how to actually get to the Trap Guard. He covers all the small details you need to actually reach the position and how to lock it up. Be sure to drill this otherwise you'll have trouble getting into this spot.