The tag "transgender-mtf" is a description used in adult content. It specifically refers to a pornographic video involving a transgender woman, also known as a male-to-female (MTF) individual. In this case, MTF refers to the process of transitioning from male to female, which may include hormone therapy and various surgical procedures. Therefore, this tag is a way to indicate the gender identity and experience depicted in the video. It's important to note that this tag is meant for adult audiences who are familiar with pornographic content, as it describes adult themes involving transgender individuals.