A video mashup is the combination of multiple sources of video—which usually have no relation with each other—into a derivative work, often lampooning

Parody

A parody , in current usage, is an imitative work created to mock, comment on, or trivialise an original work, its subject, author, style, or some other target, by means of humorous, satiric or ironic imitation...

 its component sources or another text. Many mashup videos are humorous movie trailer parodies, a later genre

Genre

Genre , Greek: genos, γένος) is the term for any category of literature or other forms of art or culture, e.g. music, and in general, any type of discourse, whether written or spoken, audial or visual, based on some set of stylistic criteria. Genres are formed by conventions that change over time...

 of mashups gaining much popularity. To the extent that mashups are 'transformative

Transformation (law)

In United States copyright law, transformation is a possible justification that use of a copyrighted work may qualify as fair use, i.e., that a certain use of a work does not infringe its holder's copyright due to the public interest in the usage...

' of original content, they may find protection from copyright claims under the "fair use

Fair use

Fair use is a limitation and exception to the exclusive right granted by copyright law to the author of a creative work. In United States copyright law, fair use is a doctrine that permits limited use of copyrighted material without acquiring permission from the rights holders...

" doctrine of copyright law.