SFM stands for Source Filmaker, which is a video game content creation tool developed by Valve Corporation. It allows users to create and manipulate 3D models, animations, and environments from various Valve games. PMV stands for Porn Movie Video, indicating that this porn video contains animated or live-action scenes featuring the Source Filmaker's assets or characters. Therefore, the tag "sfm-pmv" refers to a pornographic video using content created with the Source Filmaker tool in a porn movie format.