WatchKnowLearn. This site is amazing. It features close to or more than fifty thousand videos about every topic imaginable. The creators of the site list is a free domain to categorize and rate K-12 educational videos.
It reminds me a little of scoop.it or pinterest for video links. It provides teachers the capability of adding links to videos about topics. After adding the links, a team from WatchKnowLearn sifts through the videos and determines if they are right for the site, they are added to a large database where anyone can access them.
I love, love, love how this site it checked and maintained and evaluated for good sources. There are many opportunities. Teachers can actually set up a classroom on the site and assign videos to classes and students. There is a step by step instruction sheet as well as a video about creating the account and the classroom. What's even better, all of it is free! One tip, someone has to be an administrator so talk to people at your school and see who that would be. Enjoy! It's a great tool