video tutorial about holes in a terain...

Hi there, I know that there are tones of threads about solutions on making holes on a terrain, but I am looking for a specific way that has been described in a video tutorial (don't remember whether was official or user edit):

To be more specific, in that video there was the plane and a ball. The tutor/user used a tool or shader to "paint" a round hole on the terrain. The ball circumference was bigger than the hole. The outcome was that when the ball was driven in that hole, it was falling inside and stood there. To be more accurate, the area of the ball that was in the hole was disappeared, so the tutor did something more so not to disappear the part of the ball that was in the hole. If it helps he also used a "ring" around the hole for aesthetic reasons. Anybody has any idea what was that video?

Not a good picture of what I remember but hopefully, it will give you an idea,...