Welcome to the movie project!
It doesn't have to be a webcam.
actually, a normal Camera is preferred since the picture will be better.
Example: You are a civillian who sees zombies outside your window (if you want zombies in your scene(s), REMEMBER the zombie rules, what they can and can't do. this is gonna be a realistic movie) and grabs a camera to film them, while screaming out how weird all this is. That would make for a quite good scene.