This porn video tag can be broken down as follows:
1. Gay: The content of the video features same-sex activity between men, specifically male anal penetration and other acts typically associated with homosexuality.
2. Black Guys: The participants in this video are African-American or black men. This term specifies the ethnic background of the performers involved.
So, the tag "gay-black-guys" refers to a pornographic video that shows explicit sexual activity between two or more black men.