You can read a summary of the key points from the video below, but I think it is worth bearing in mind that Chuck was a professional fighter at the time and the level of contact he employs is relevant to that. There is nothing wrong with toning down (or even completely removing) the contact. You can still get a lot out of this exercise without risking a few bruises.
Key Points
* Be careful to train at a level at which you are not getting injured.
* They are hitting at 75% power to the body and open handed to the face while avoiding the eyes and the eye area.
* Mix up the positions from where you start the sparring from.
* When practicing ground and pound, concentrate on that. This isn't a full out sparring session and neither participant is trying to get a submission or practice escaping and standing up for example.
* Notice that the thighs are viable targets. Practice striking there also.
* Notice that while striking Chuck is keeping one hand pushing down on his opponent to help keep him pinned in place. This can be dangerous when done from the mount against someone who knows BJJ submissions.
* When using the focus mitts be careful not to hold them directly in front of your face as the impact may drive the mitt back into you.
* Practice striking from your back also, not only when you have control.
