"Con" in the context of a porn video tag is likely short for "confinement" or "bound." In adult content, it refers to situations where individuals are restricted, confined, or bound in some way during sexual activities. This could include being tied up or restrained, having body parts immobilized, or being locked in a specific position. The term is often used as a keyword for BDSM and kink-related scenes that involve bondage or restriction play.