These are additional sites I’ve found with FREE footage clips.
This one is not for commercial use, but if you’re just putting up a video on youtube and not charging for it, you can use them.
This next one is quite unique — open source film! In their own words:
“Stray Cinema is an open source film. On this website you are able to download and re-edit professionally shot raw footage from a feature film, providing people from all over the world with an opportunity to create their own version of the film.”