How to cite/reference a TED or TEDx talk depends on whether it is on TED’s website, or on another site such as YouTube.
TED talk on TED’s website
The speaker is credited as author. Example: Philip Zimbardo’s February 2008 TED talk titled “The Psychology of Evil” on TED’s website.
Zimbardo, P. (2008, February). The psychology of evil. [Video]. TED Conferences. https://www.ted.com/talks/philip_zimbardo_the_psychology_of_evil
In-text citation: (Zimbardo, 2008)… or …Zimbardo (2008)… or if you have quoted directly, e.g. (Zimbardo, 2008, 5:58) would be a quote starting at 5 minutes and 58 minutes in.
TED or TEDx talk on another video site
The uploader is credited as author, even if they are not TED or the speaker. For example, Raj Persaud’s TEDx talk on “The psychology of seduction” which took place at the University of Bristol.
Reference:TEDx Talks [TEDxTalks]. (2016, July). The psychology of seduction | Raj Persaud | TEDxUniversityofBristol. YouTube. https://www.youtube.com/watch?v=3E46oWB4V0s
In-text citation: TEDx Talks (2016)… or (TEDx Talks, 2016)… If you wish to credit the speaker, work his name into the text. For example, “In 2016, Persaud argued that choice of partner was crucial (TEDx Talks, 2016)…”