Although the standard license in YouTube is not Creative Commons, contributors can elect to publish their videos as CC BY. Once you search for a video, you can filter the results by license and get a list of all the Creative Commons videos.
“Launched in May 2005, YouTube allows billions of people to discover, watch and share originally-created videos. YouTube provides a forum for people to connect, inform, and inspire others across the globe and acts as a distribution platform for original content creators and advertisers large and small.
YouTube is a Google company.”