C-SPAN is a public service created by the American Cable Television Industry, and contains footage of the gavel-to-gavel proceedings of the U.S. House of Representatives and the U.S. Senate, and to other forums where public policy is discussed. Most of it is free to download and reuse; create a free account to download lower-quality clips for free. High resolution clips are a modest fee.
FedFlix has films produced by the United States Government, from training films to history, from our national parks to the U.S. Fire Academy and the Postal Inspectors. All of the content is available for reuse without any restrictions whatsoever.
A free archive of streaming, U.S. News content. Searchable by closed captions from the major cable and broadcast television networks from 2009-present. Streaming videos are not available for download, but users are able to borrow DVDs of each show. Transcripts are available for each show.
FreeStockFootage.com offers a large collection of free and low cost HD and 4k video stock footage, B-Roll, and motion graphics downloaded by the clip. Clips can be used for personal, corporate, and commercial productions, as well as blogs, social media, advertisements, web and mobile applications, and more.
An older website created by the UNC Chapel Hill Libraries, this site provides video clips from a variety of sources, especially U.S. government agencies such as the U.S. Records and Archives Administration and NASA. Free to download and reuse for Fair Use, though much of the content is low-resolution and some of the files are no longer available (the site does not look to be actively maintained.