Thank you all for your help. The Energia website mentions a Mikrovit kit; Google search for Mikrovit returns fish food and zinc fertilizer, both of which are rather unlikely in this context. Also there does not seem to be heritage to this experiment, while the Advanced Plant Habitat builds upon VEGGIE and older experiments on Mir and Salyut Space stations, Probiovit seems to be new experiment. I saw the video linked and used the automatic translation of the subtitles into English to try to understand what it was saying, and it seems to confirm that it is a brand new experiment. Also if I understood the badly machine translated subtitles the cosmonauts will eat 20% of the kefir and send the rest down to earth for testing and experiments. Yurchikin, who has a Greek mother, does speak Greek, albeit with a very strong accent, I wish that he would have narrated that video in my language.
To summarize what you have all shared with me: It is an experiment called Probiovit run by Energia. The idea is that for long term space flight such as the trip to Mars cosmonauts will be able to transform milk getting to expiration date to kefir so as to extend food shelf life. They will use freeze dried milk in the experiment, which seems to be a standard product in the food supplies of the ISS. The experiment will also be monitored through images and video from the ground, in addition to the cosmonauts. Most of the kefir will be taken to Earth for testing but some 20% will be kept on the station and be eaten by the crew, eventually like VEGGIE.
If I missed or misunderstood something let me know. If something else gets posted on the web and eventually when something gets published, let's put it on this thread.