The tag "cd-masturbating" refers to a specific type of masturbation in the context of porn videos. In this case, "CD" is an abbreviation for "Cock and Dildo," which means that the scene involves both a man's penis (cock) and a sex toy (dildo). The tag describes a video where the individuals involved are engaging in masturbatory activities using their own genitals and the dildo, typically for the purpose of sexual pleasure.
In the video, one or more individuals will be seen touching, stroking, and stimulating their genitals with their hands while also inserting the dildo into either their own anus or vagina (or using it on a partner), to create a mutual pleasure experience. This type of scene often showcases different techniques for self-pleasure, as well as various positions and combinations of both sex toys and human bodies.