Building Takes Time

[Need_Help]

Sorry of this if it had been discussed before or posted before.

In C4 will we have the chance to see building takes in-game time to build or it is just like C3(which is finished building when you press the mouse button).And what is this movie shows??(In the E3 06 Gameplay 2 movie)Is it the building takes time to build??Or the building is upgrading??And will the building have snow on top of the roof??(Because it looked like snowing, but im not sure whether it is snowing).

Thanks

E3 06 Gameplay 2 in pc.ign
http://media.pc.ign.com/media/766/766546/vids_1.html