In this video Coach Carl is still working on hand position and the pulling mechanics. He uses a fat bar to change the bar width. It forces you to get your pinky knuckle over the bar and it forces you to increase grip strength. No, we do not have this specific bar- but we do have a dog bone which may substitute for the fat bar. Ask a coach if you need help.
Coach Carl talks about starting with your hand grip narrow and close, then moving to a wider grip, then the natural over grip. Check out the video below and keep working on your pull-up progressions and grip technique!