It is probably one of the most important things a videographer or photographer can do, backup the least once or why not twice! I have a photographer friend that actually drives her backup drive to another location and keeps another drive with her for editing purposes, just in case of a fire or whatever other catastrophe could happen at home. 

When selecting your videographer, it would be wise to ask just how many times they back up the data and where it is stored cause even if a meteor doesn't crash through the roof, a drive could always fail. 

Happy hunting!