Public Domain and Royalty-Free Sources
Sources That Have Multiple Varieties of Media.
The Internet Archive.
The Internet Archive is a non-profit library of millions of free books, movies, software, music, and more. Much of the material is in the public domain or licensed under the Creative Commons license. Make sure you check each piece for restrictions and usage rights.
Pond 5 Public Domain Project
Pond 5 is a major supplier of media clips and a good place to sell your own stock footage, images, music and sound effects. But, in addition to the media they have for sale, they have established a section of public domain media that is available for download at no cost. You’ll have to set up a free account to download the clips, but it’s worth the effort. Most of the clips and stills appear to be European and there are a lot of WWII vintage items. There are some good classical music cuts in the audio section.
Pixabay has over 1.3 million images and videos. All contents are released under Creative Commons CC0, which makes them safe to use without asking for permission or giving credit to the artist – even for commercial purposes. The Pixabay site has photos, vector graphics, illustrations, and videos