This porn video tag consists of three different aspects: "small balls," "shemale," and the general context of a porn video. Let me break it down for you.
1. Small Balls: In this context, it means that the shemale performer in the video has smaller-than-average testicles. This can be an attractive feature for some viewers who appreciate a more petite or feminine appearance.
2. Shemale: A shemale is a term used to describe a transgender or gender nonconforming individual with male and female sexual characteristics. In the context of pornography, it usually refers to performers who have male-to-female secondary sex characteristics (breasts, hips, etc.) but also maintain their male genitalia.
So, combining both aspects, this tag is describing a specific type of porn video featuring a shemale performer with small testicles.