Those videos are for the old version of SceneTerrain, the last one for Blender 2.79. SceneTerrain is being merged into SceneCity progressively with more features and flexibility, so in time it will no longer be a separate addon.
If you don't intend to use Blender 2.79, look in SceneCity's documentation for the terrain features.
Call me Arnold. I'm an independent developer and artist. I've been programming and using Blender for more than a decade.
