Fair use, a limitation and exception to the exclusive right granted by copyright law to the author of a creative work, is a doctrine in United States copyright law that allows limited use of copyrighted material without acquiring permission from the rights holders. Examples of fair use include commentary, criticism, news reporting, research, teaching, library archiving and scholarship. It provides for the legal, non-licensed citation or incorporation of copyrighted material in another author's work under a four-factor balancing test. The term fair use originated in the United States. A similar principle, fair dealing, exists in some other common law jurisdictions. Civil law jurisdictions have other limitations and exceptions to copyright.
For further info check out the wikipedia article on fair use. Too long to copy and paste. How do you plan on profiting from doing reviews on YouTube?