Yes, you'll have to delve into motion/planar tracking. That's a way to record an item's movement thru a clip. Then with that info, you can replace, for instance, a word with another. Google for Mathias Mohl. His website mamoworld.com has tutorials considering what you want to do. If you need to do this project first, go ahead; you'll learn a lot. But don't skip over the basics when you're done.