There are three major insurance categories that every filmmaker should recognize.
General Liability Insurance:
Is basically what it sounds like. It covers against damage to the filming location and space, also injury to those present that are not working on the film.
Video Equipment Insurance:
This insurance is probably the most commonly used during production of a film. Equipment insurance covers any and all film equipment used in your filmmaking process and production. This policy will cover loss, damage, theft, etc. to your rented or owned equipment. Often you can get insurance on rental equipment for 10% above the rental cost.
Errors and Omissions Insurance:
This type of insurance protects against lawsuits alleging unlawful usage of titles, copyrighted materials, ideas, formats, characters, plots, plagiarism, unfair competition, defamation and invasion of privacy. E&O insurance sometimes requires the counsel of an entertainment lawyer who will review your script.
All three of these insurance policies differ between the types of films you are making short-term, long-term and annual or short documentary to feature film.