The names of the months in this video are not in their dictionary forms - instead, they are all in the Genitive case. Why, you ask? It's because these are the forms used in Russian dates! The genitive case roughly corresponds to when we use the preposition "of" in English, and is a very widely used case in general. Luckily, all the month names are masculine and quite similar-sounding, so their genitive forms will be easy enough to remember!
