TED Ed

TED Ed is an education initiative from TED to help teachers, educators, and students to access and create interactive video lessons.

https://ed.ted.com/

Youtube is fantastic for random videos, but if you want to challenge your students to think, TED and TEDed are videos on subjects that you can literally plug into your classroom and get the conversation started. Engaging, dynamic, insightful, even if you or your students don't always agree with the speaker, it'll be worth your time to watch for the conversation that follows. Plus they make full transcripts and embeddable videos to add to your own LMS if you are so inclined!