You must credit the creator in your video description or liner notes.

The BBC has made thousands of their archival sounds available for personal and educational use. It is a fantastic resource for high-quality, historic foley. 3 Tips for High-Quality Audio Searching

A massive community-driven database. It is best for raw, organic sounds like "rain on a tin roof" or "city ambience." Just be sure to check the Creative Commons license for each file.

Who is your ? (Beginner vloggers, pro game devs, etc.)

Instead of "car sound," try "vintage car engine idling" or "fast sports car drive-by."

You can use it for anything without giving credit.