Here are some of the (many!) places you may wish to begin your search for open educational resources:
The following are tools which allow for cross-searching multiple OER platforms and resources.
Please note that while some repositories listed below contain public domain or Creative Commons-licensed videos, many include videos that are freely-accessible, but not issued with an open license for reuse or adaptation. In such cases the videos should be accessed by a link.
"Open Educational Resources: Finding OER" by Wellesley College Library is licensed under CC BY 4.0 / A derivative from the original work by BMCC Open Educational Resources.