[WDHewson]

I did, the use was in a video, education exemption did not apply.

The ultimate proof would be the result of an infringement trial.

TedTalk speakers are unpaid.  And you'd be hard pressed to call them non-educational.  There is a lot of latitude in interpreting the following.....

Copyright Disclaimer Under Section 107 of the Copyright Act 1976, allowance is made for "fair use" for purposes such as criticism, comment, news reporting, teaching, scholarship, and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. Non-profit, educational or personal use tips the balance in favor of fair use.