Use a film for which permission is not required.
Although the rules for determining the duration of protection can be complicated and may depend on facts that are simply undiscoverable without many hours of research, one bright line rule does exist: any work published in the U.S. before 1923 is in the public domain.

Many copyright owners offer their works to the public with few or no restrictions. To use these works, make sure that the owner has given explicit permission to the public and heed any restrictions that may prohibit your planned use.

Sources of information about films that are in the public domain or have been offered to the public and how to obtain them include the resources listed below.

Use a work created by the U.S. government.
Works created by the federal government are not protected by copyright. However, works commissioned by the federal government and state government works may have copyright protection.




The Open Video Project (HIGHLY RECOMMENDED!)
The purpose of the Open Video Project is to collect and make available a repository of digitized video content for the digital video, multimedia retrieval, digital library, and other research communities. This repository is hosted as one of the first channels of the Internet 2 Distributed Storage Infrastructure Initiative, a project that supports distributed repository hosting for research and education in the Internet 2 community.
BuyOut Footage
Public Domain And Royalty Free Stock Footage - contains U.S. Government resources
National Aeronautics and Space Administration
NASA videos available - a U.S. Government resource
Entertainment Magazine Public Domain Videos
These free movies are digital copies of popular full-length motion pictures produced over the last century. All of the public domain movies are legal downloads, legal to transfer to a mobile device or PC and free to watch online.
OpenFlix
OpenFlix provides a directory of movies commonly thought to be in the public domain and works their owners are willing to let be distributed.
Festival Films
Festival Films offers the largest selection of public domain feature films in the world. Quite a promise, but our associates devoted lifetimes and fortunes to finding EVERY FILM they can that is in the public domain. Films are said to be in the public domain because they were never properly copyrighted in the first place or were not renewed as required by law.
Internet Archive Moving Images Collection
This library contains thousands of digital movies which range from classic full-length films, to daily alternative news broadcasts, to videos of every genre uploaded by Archive users. Many of these movies are available for download.
Reel Media International
Reel Media library contains Public Domain Movies, Public Domain TV Series, Public Domain Documentaries, Public Domain Cartoons, and other Public Domain television programs.
Desert Island Films, Inc.
Desert Island is a database filled with Public Domain films. Requires purchase to obtain them though.