As @seraphim-serenata put it, this is a less pussified version of self mutilation as we have seen recently. Videos like this give us faith that not all cutters are attention seekers. Some actually mean business.
In the video, a self mutilator performs a single slice along the forearm with a razor blade. The slice is pretty deep, and it takes almost two pairs of hands to keep it shut.
Thanks a lot for the video, @seraphim-serenata: