If you're working on a research paper or presentation, including images or video can be pretty straightforward. The main thing to remember is that using images isn't the same as quoting text, even if they're from the same source.
You usually won't alter the image and will have room for attribution, either on the presentation slide or in a References list at the end.
Fair Use allows copyrighted work to be reproduced for certain types of uses—such as criticism, comment, news reporting, teaching, scholarship, and research. If you're only using a small portion (an image or a short video clip) in a project that will only be shown to your teacher and classmates, you're probably protected by the Fair Use clause.
The Creative Commons search tool allows you to search for images, music, video, and other media that have been given a "Creative Commons" license. Depending on the license, you can use the results for commercial or noncommercial projects or modify or adapt the image.
You still have to cite items you find in the Creative Commons. In fact, one condition of all CC licenses is attribution. For citing items from the Creative Commons, refer to their "Best Practices for Attribution" page.
This work, "90fied", is a derivative of "Creative Commons 10th Birthday Celebration San Francisco" by tvol, used under CC BY. "90fied" is licensed under CC BY by [Your name here].
You can find more information on UAB's MLA Style guide.
MLA 8th Edition