The term "hegar" is likely a misspelling or typo of the term "HE-GA" which is Japanese for "Cowgirl position." In this case, the intended meaning of the porn video tag is the cowgirl position, a common sex position in adult content. In this position, the female partner assumes control and rides her male partner's penis, either facing their partner (reverse cowgirl) or facing away from them (classic cowgirl). This position allows for deep penetration and a variety of stimulation options for both partners.