One of the coolest new trends in decorating is Projection Mapping. You can pull off some truly jaw-dropping visual effects with this technique. Check out the following video:
Amazing, right? Conceptually, it's pretty simple. Your house (or a building) is a structure comprised of rectangles, columns, arches, circles, curves, and other geometric shapes. You can create a specialized video that maps animated images (or videos) onto the surfaces of these shapes, and gives the illusion of movement and activity that would be physically impossible (or impractical) in the real world.
Enter the projector. Perspective matters. Here's an example of the challenge. Let's say the blue rectangle below represents one wall of your house.
But, let's say that you cast an image consisting of a red rectangle from a projector located at the perspective shown. The red rectangle doesn't align with the wall surface, so the projection doesn't work, visually speaking.
What you really want to do is align the projected image in three-dimensional space with the wall of the house.
Tutorials Programs like Adobe After Effects make this fairly simple to do. Here's a pretty good video series (although intermediate-level) that demonstrates the technique.
Stock Footage
You can find plenty of free stock footage online, but be careful. Some of this stuff is very realistic and might elicit a visit from your local fire department.