Free video
To be a free video - referring to freedom (as in free software), not to price - a video's entire content must be previously licensed under a free content license. A video is considered legally unfree if any portion of the video was previously licensed under a proprietary license that restricts usage and prevents derivations and commercial usage.
Thus, a video cannot be considered free if it includes snippets or whole copies of any text, image, video or audio that has been previously licensed under a proprietary, unfree license. The legal concept of fair use of a third party's music or other content in one's own video work may protect against Digital Millennium Copyright Act takedowns.
However, in the 2008 court case Lenz v. Universal Music Group Inc., Universal Music Group argued that fair use did not have to be considered before issuing a take-down. The case focuses on the usage of a song licensed by Universal that was used in a YouTube video of a dancing toddler.