How to add "AR" elements over video?
I produced a video on Augmented Reality, for a large corporation that spearheaded the technology. We used After Effects to simulate a lot of effects. 

We shot our plates and scenes, and when necessary we added dots on sticks for tracking points. 

Then, you can take your footage into AE, latch motion trackers to the dots (if your scene doesnt have points sharp enough to tack to), and once you track the motion, you can nest your AR graphics, either static (photoshop psd files), or animated, and they will move with the camera movement, as if in the scene. 

If you want to go the extra mile, you can make the AR layers 3D, and add a camera, and using multiple tracking points get your AR graphics to move in 3D, with axis tilting. 

You can also add things like Depth of Field. 

And lastly, you can have them build on and build off using the built in transitions in AE under Animation... there are 100s. 

Hope this helps, Its more than one could explain here, but there are a lot of youtube videos on how to use motion trackers, 3D layers, etc- so if you look into the keywords I gave you, hopefully it will get you started. 

Cheers!