Q. How do I cite a video from a site like YouTube?
If you are using an online bibliographic referencing tool, then select to create a reference of type "Video" or "Movie" -- and put in the link.
For example, to cite this video on the Numberphile YouTube site -- https://www.youtube.com/watch?v=4Lb-6rxZxx0 -- enter all the details into an online bibliographic referencing tool.
In your Works Cited or Bibliography, the movie or video entry should look something like this in the alphabetical listing in MLA style:
Numberphile. “Monty Hall Problem - Numberphile.” YouTube, 22 May 2014, https://www.youtube.com/watch?v=4Lb-6rxZxx0. Accessed 17 Jan. 2017.
In the body of your paper, this information source will be referenced like this -- as in-text citation in MLA style:
A very good explanation of the Monty Hall problem was given by a statistics professor at the University of California Berkeley (Numberphile).