The reason for the increase in descent rate is quite obvious. The pilot flying asked for the pilot not flying to inhibit the glide slope warning so at that point he could descend below the glide slope to have more runway available to him at touchdown. A normal 750 fpm rate of descent would then go to 1200 fpm to accomplish that. Most of us have done it many times. I have many times with positive results. It was done below 200 ft. Check the CVR.