What do you want from your video? You should have an idea of your expectations before signing up, ask lots of questions about what your end product will look like. DO you want lots of prep shots? DO you want the videographer to be more focused on your family? Your videographer wants to capture what is most important to you, just make sure they know what that is.
Relates Searches
The Knot: https://www.theknot.com/content/questions-to-ask-your-wedding-videographer
The Bridal Guide: http://www.bridalguide.com/blogs/the-budget-guru/wedding-videographer
Allyson Vinzant: http://www.allysonvinzant.com/questions-to-ask-your-wedding-videographer/