In the movie "Адмиралъ" there is a scene where Admiral Kolchak recites some parts of the Russian Bible which, it turns out, is written in Church Slavonic. But it seems that fellow sailors understand what he says. Even I myself could spot many familiar words. Is that language close to modern Russian? Do contemporary Russians understand Church Slavonic? If they do, they must be able to understand other Slavic languages too, as Church Slavonic is the mother of all Slavic languages...
In particular, do Russians and Yugoslavs understand each other?