Below are some good platforms to search for CC licensed or public domain videos to use with students in class. I invite you to check them out and share with us if you have other suggestions to add to this list,.
YouTube has a handy filter in its advanced search that allows you to look for Creative Commons licensed videos. Here is to use it :
Run your search query on YouTube then in the first search result page, click on "filter" then choose Creative Commons from under "Features":
2- CNN Students News
CNN Student News is a ten-minute, commercial-free, daily news program designed for middle and high school classes. It is produced by the journalists at CNN. This award-winning show and its companion website are available free of charge throughout the school year.
NASA ha this wonderful page where you can have access to a wide variety of video collections to download and use with students in class.