In this gay section, massage refers to scenes built around hands-on bodywork: oil, rubbing, tables or mats, and the setup of one person working on another. The term points to that framing rather than to any particular act that may follow. Related vocabulary you may see near it includes anal, blowjob, big cock, bareback and compilation. Bareback is a term about condom use, not a separate act, while compilation describes a clip assembled from several segments. Massage itself stays focused on the physical setting and the contact involved.