The phrase "purple-heart" in the context of a porn video tag is most likely referring to the "Purple Heart" award, which is a military decoration awarded to individuals who are wounded or killed while serving in the United States Armed Forces. This term may be used as a metaphor for an act involving someone with a military background or theme, or it could be a name given to a particular scene or video related to this topic. However, without further context, it's difficult to determine the exact meaning of "purple-heart" in this specific case.