2. Why shouldn’t I just have a friend or relative video it for free?

There is a huge difference between home videos and professionally produced and edited videos. The quality of the cameras, sound and post production equipment are not even close to your average home movie. Unless your friend works in production for a living, they're not going to have a professional editing suite or know how to use one. The best question to ask yourself is, "Do I want to risk my special day in the hands of an amateur?"