Mylene Farmer and Olivier de Sagazan smear grey clay and some paint over their faces in the music video to "A l'ombre". Apart from the two there are also some male dancers dancing in rain on the muddy ground.
Mylene Farmer got the inspiration for her video from Olivier de Sagazan's work "Transfiguration", in which he smears clay all over his face. Olivier de Sagazan did another work called "Hybridation", where he and one other person play with clay and smear it over themselves in the same manner. He did multiple of these "Hybridation" live performances with various people. Here is one he did with Stephanie Sant in Greece (see the last 3 pics)