Editing map ingame?

So as you can see in the clip, the map changes. How was this done? Is it possible to trigger a rise or fall in the map ingame(Code)??? if so by any means how?

anyone tried this, please send me link.

https://developer.valvesoftware.com/wiki/Env_terrainmorph

The wiki page says that the feature was taken out in 2007, and never worked very well anyway.