The term "pits" in the context of a porn video refers to a specific fetish or kink, involving wax play. In this case, it is related to the act of using hot or warm wax on sensitive areas of the body, such as the nipples, inner thighs, and other erogenous zones. The wax is applied and then quickly removed, either by pulling away from the skin or using a cloth, creating a slight sensation of pain which can be highly arousing for some individuals.
Pits could also mean "pussy" in some languages, referring to female genitals. So, it might be used as a tag for content featuring cunnilingus or close-ups of the female genitalia.