The "mad scientist" seems to be Anatoli V. Brouchkov, one of the authors of Draft Genome Sequence of Bacillus cereus Strain F, Isolated from Ancient Permafrost, detailing the organism's name as "Bacillus cereus Strain F", not "Bacillus F" as so commonly plagiarised in connection with this sensational news bait. Other subjects beyond what he did to himself make up a highly unusual minority group at best.
In that video from the DailyMail Brouchkov is quoted explicitly and on tape himself (starting at 5:45 min):
Narrator: "Anatoli Brouchkov tested an extract of the bacteria on mice and has taken it himself. Though he says it's a food supplement. So Manoush's decision to inject is a new, possibly riskier stage of the experiment."
Brouchkov: "I didn't recommend her any injections and I told her it was no injection. It was just, ah, consuming the extract of the bacteria. Well, I, what I can say. She is a very brave lady."
That makes the conclusion quite obvious that Brouchkov did not inject living bacteria into himself.
In whatever way he took the bacteria or an extract of them: his claims are not about injections, but about improved health in test animals and himself. Any claim about "injections" is up to the media to substantiate, sometime perhaps?
More factual reporting, even as events unfold, seems to have been possible in this case:
Anatoli Brouchkov, head of the geocryology department at Moscow State University, says he drank million-year-old bacteria, and he tells the Russian TV network RT that he’s been working longer and hasn’t gotten the flu in two years.
A more balanced account on the surroundings of this experiment is found here: some lifeforms may have been alive since the dinosaur era. A first clue into these claimed "benefits" of introducing the bacteria to currently living organisms is published in: Relict Microorganisms of Cryolithozone as Possible Objects of Gerontology:
Testing Bacillary Cultures in Higher Organisms
Testing in Drosophila melanogaster:
The experiment was carried out in Drosophila melanogaster flies of the same age (24 h). Five pairs were placed in test tubes with a nutrient medium (5–7 ml). The volume of sampling was 100 flies for each group. Flies were selected for the experiment by etherization; the dead and surviving flies were counted every 3 days. The experiment was carried out with a 24 h culture of Bacillus sp. (strain 3M) grown in a meat–peptone broth. The culture (20 μl) was added to the test tube with the experimental group. In the control group, the flies were kept in the medium with yeasts; in the experimental group, the flies were kept in the medium with yeasts for the first 5 days and then in the medium with the bacillus for 24 h (alternated during the whole period of observation).
And that is a very preliminary study design. One group with this bacterium, the other without these bacteria (possibly sterile?). A better design would have included "younger" or just other bacteria to compare with the current experiment and control groups. Either way, the results were less impressive than popular headlines:

Improving on this design flaw the same author tried two different strains of bacteria against a control:
Permafrost Bacteria in Biotechnology: Biomedical Applications
Effect of treatment with Bacillus cereus var. toyoi and Bacillus cereus strain BF on mortality in outbred mice after oral inoculation with S. enterica var. enteritidis (5 × 106 CFU per mouse on day 0; ten mice in each group):

Note that both bacteria are shown to have some effect in this very small sample study. However, the one strain showing an effect here is not particularly known to be very effective either (Development of intestinal microflora and occurrence of diarrhoea in sucking foals: effects of Bacillus cereus var. toyoi supplementation: We conclude that the supplementation of B. cereus var. toyoi had no effect on the occurrence of diarrhoea and health status in the foals.)
They followed this up with the detailed speculation on possible mechanisms:
The following three basic mechanisms could be proposed for how orally ingested nonindigenous bacteria can have a probiotic effect in a host:
- immunomodulation, that is, stimulation of the gut-associated lymphoid tissue, e.g., induction of cytokines;
- competitive exclusion of gastrointestinal pathogens, e.g., competition for adhesion sites; and
- secretion of antimicrobial compounds which suppress the growth of harmful bacteria (Duc et al. 2004).
We propose that the notable probiotic properties of Bacillus cereus strain BF as compared with Bacillus cereus var. toyoi can be explained by the production of unknown bacteriocin-like inhibitory substances (unpublished data). We described the S. enterica var. enteritidis model as a variant to cause a chronic carrier state in mice after oral inoculation, as a model for a human carrier state. The pathogenic mechanism of S. enterica var. enteritidis action was connected with the gastrointestinal tract. Therefore, we used oral infection and treatment of mice. To protect mice from Salmonella infection, antibiotics or bacterial extracts can be used (Deng et al. 2007). Viable microorganisms such as yeast and bacterial species have been used to protect mice from Salmonella infection (Szabó et al. 2009). In our case, Bacillus cereus strain BF protected mice from Salmonella infection. Probiotic bacteria reduced colonization by pathogens and decreased host defense mechanisms. Preliminary results for Bacillus cereus strain BF showed an increase of the humoral and cell immunity of mice (Brouchkov et al. 2009). Thus, the possibility of oral treatment of mice infected with S. enterica var. enteritidis with probiotic Bacillus cereus strain BF, obtained from relict permafrost, was clearly demonstrated.
Given the assumed age of this strain, whether it was "living", that is metabolising, the whole time or just thawed up and reactivated, it is possible that this variant is one of a non-pathogenic subspecies. Maybe it outcompetes pathogens, maybe it has pro-biotic effects:
Probiotic Activity of a Bacterial Strain Isolated from Ancient Permafrost Against Salmonella Infection in Mice.
Other lines of inquiry may lie in specific compounds produced by this species, for example certain lipopeptides: Agricultural Sciences
Effects of Bacillus cereus F-6 on Promoting Vanilla (Vanilla planifolia Andrews.) Plant Growth and Controlling Stem and Root Rot Disease.
Or DNA-repair enzymes An unprecedented nucleic acid capture mechanism for excision of DNA damage (2010) or similar mechanisms of various types A new protein architecture for processing alkylation damaged DNA: the crystal structure of DNA glycosylase AlkD (2008).
Whether this species simply lost its pathogenic potential, never developed it in the first place, all bacteria do stimulate an immune response.
The official word on probiotics and their relation to "flu" or more precise the common cold is currently:
The evidence that probiotic supplements may help to prevent colds is weak, and little is known about their long-term safety.
Currently there is some interesting research going on. As preliminary tests and studies the design problems encountered so far are forgivable. But since they were always present, no definitive answer can be given to that question. Even for other species of bacteria known, used and investigated since 1917 we do not have a complete picture of what they do or how they do it (Upregulation of Intestinal Mucin Expression by the Probiotic Bacterium E. coli Nissle 1917 (2012): The probiotic E. coli Nissle 1917 (EcN) has been reported to have various health benefits; however, very little is known about their underlying mechanisms.). The cereus group is much less well studied for basic functioning or health effects. (E.g. The putative drug efflux systems of the Bacillus cereus group (2017).)
Brouchkov's own assessment in peer reviewed journals now says:
Permafrost microorganisms are possibly a perspective object for the search of new probiotics. (First Online: 24 June 2017)
Whether he really injected himself with living bacteria, with inactivated/dead bacteria or whether he only ingested them:
He told The Siberian Times, “After successful experiments on mice and fruit flies, I thought it would be interesting to try the inactivated bacterial culture. […] “The permafrost is thawing, and I guess these bacteria get into the environment, into the water, so the local population, the Yakut people, in fact, for a long time are getting these cells with water, and even seem to live longer than some other nations. So there was no danger for me.”
However, he admitted that he had no idea what the bacteria was actually doing to his body, as scientists are not yet sure exactly how it works as they claimed “we cannot understand the mechanism, but we see the impact.”
'Now we have applied for a grant to conduct further research, especially on human blood cells, and we hope that we will get it, because the research is extremely promising.'
This article, or one like that (in other Russian newspapers) seems to have started this whole thing. Note the mismatch between headline and body text regarding 'injections'.
– Conclusion –
As an anecdotal evidence Brouchkov claims about his personal health are irrelevant. If he were to market this strain as a probiotic, he'd have a tough time regarding these health claims in many markets. The possible effects claimed more by certain media than by him from a one-time shot of dead bacteria are wholly unlikely. For any effect over the claimed time span the procedure would have to be repeated. Live bacteria might have colonised him (that would be easily testable, but was apparently not carried out) and show beneficial effects (although that too is not very likely to the extent claimed in the articles in question). Most of the possible reasons for "health benefits" given by Brouchkov initially ('the bacteria are old, … therefore you grow older'/'exotic people living where we found them get older than expected…') are just nonsense.
More accurate headlines would have to read like:
Russian geocryologist (scientist specialising on permafrost soils) finds 3.5 million-year-old bacteria in thawing Siberian soil, assumes after preliminary testing the bacteria's potential as a trendy pro-biotic, eats it, says he is fine.
and as a follow up:
Global yellow press goes ape over misleading headline involving "Russian Scientist" – For years now, media fails to do basic research and just copies outrageously exaggerated claims over and over – Possible harm to actress
Only one effect of this bacterium is crystal clear: it makes you immortal – by getting you into the news.