As a minimum, we would always suggest that a film library has professional indemnity insurance.
When a film library holds such a huge collection of footage, it’s incredibly difficult to ever be 100% sure on the origin, authenticity and clearances obtained for any clip. Unless one person has personally created all the footage, which is not the case for most large film libraries which have hundreds of contributors.
If a film library has employees, it also crucial that you have liability insurance to comply with the law. More often than not, libraries are also considering cyber insurance to protect from hacker attacks on their database and collection. In addition, if you have an office you may wish to insure the office, computers laptops etc.