It is often sufficient simply to describe web pages and other website content in the text (“As of May 1, 2017, Yale’s home page listed . . .”). If a more formal citation is needed, it may be styled like the examples below. For a source that does not list a date of publication or revision, use n.d. (for “no date”) in place of the year and include an access date.
Reference List Entries (in alphabetical order)
Bouman, Katie. 2016. “How to Take a Picture of a Black Hole.” Filmed November 2016 at TEDxBeaconStreet, Brookline, MA. Video, 12:51. https://www.ted.com/talks/katie_bouman_what_does_a_black_hole_look_like.