They're not showing that they nearly finished. They're showing how far they've got.
From the video, I gather a few things:
1. They have the main interface working (and it looks like TTD - ie it uses the TTD graphics correctly).
2. There is a landscape or map in the game.
3. The map can be moved around inside the screen.
4. They have windows in the game.
5. They have object placement (putting the trains and track in the game).
6. The trains follow the rail paths (very important step in terms of the programming).
Anybody add anything else?
The fact that the trains run through each other is very common at this stage during programming. There is a whole module called collision detection. This can be a very complex part to do. And you generally need to get all the movement of objects done before you can even start on it.
[Edit: Why does Prof. Frink always get there just before me
You're saying I'm a Dominion spy, and don't even know it! - Dr. BashirThat's the Joker in my avatar, not me. No wait it is me.