What's the joke? It seems to me they're trying to make a point about the study that appears lower on the page, the one claiming that vaccinated people are dying at a higher rate than unvaccinated.
The joke is that not taking into account all known correlated predictors when performing a statistical analysis can produce absurd results. In this case, age is a metric variable known to be a correlated predictor of what movies an individual has seen, the probability of their death due to COVID-19, and the probability of their being vaccinated against COVID-19. The precise relationship between those four items is beside the point here -- the point is just that if you did not take into account that age is a metric variable and that it is a correlated predictor of both vaccination status and death, then you did your analysis incorrectly.
Older people die more often than younger people. More older people are vaccinated than younger people.
The study at the bottom shows that vaccinated people are dying at a higher rate than unvaccinated people. The joke is on the person who concludes that the increase in death rate is because of the vaccine and not the age difference.
