Creative Commons Resources
As requested, here are some good creative commons resources for media.
An excellent source for audio, focused on sound effects. Ambient background noise tracks for various environments, samples of specific machinery, synthetic pops and clicks, it’s all here. Really easy to use too. All the foley audio for a 3D animation I made last trimester was from here (shameless plug).
Massive amounts of media on here, video and audio and everything in between. This site is better if you want to find radio broadcasts from 1947, or samples of TV ads, or weird things like that. Quite a massive site with many aspects, harder to use than Freesound.
Specifically for Creative Commons music. This is a community of remixers and authors who put up everything from drum loops to finished tracks. A lot of high quality stuff on here, and I’ve used it for projects before.