"tsfoxxy" is a combination of two elements: "TS" and "foxy". In the context of adult content, "TS" stands for "Transsexual" or "Transvestite", referring to performers who are transgender women or men who dress as the opposite sex for the purpose of sexual stimulation. "Foxy" is a slang term meaning attractive or alluring.
So, "tsfoxxy" can be interpreted as "attractive transsexual/transvestite" and refers to porn videos featuring performers who identify as transgender and are considered sexually appealing.