Rights Managed Vs. Royalty Free

Licensing is a tricky concept to grasp.  If you're creating work for educational purposes, you can pretty much use anything as long as you give proper credit and you're not profiting from it.  But eventually, ya gotta pay the bills.  This article breaks down the difference between content (videos, music, photos, etc...) being either "rights managed" or "royalty free". 

Article