Scot47 we have had over a dozen Russian visitors to our villa who share my experience of being unable to understand Bulgarian. Many of these spoke more than one language. While I am not saying you (or MW) are lying, I have to believe my experiences as you do.
Your Russian abilities must be better than mine then, I am unable to watch movies and TV shows in Russian as the speech is too quick. You would have to be thinking in Russian rather than translating Russian to English (as I have to) to be able to keep up IMHO.
I can manage with the subtitles on, but often find they do not translate everything correctly, so they keep the general gist but not translate word for word, probably would not make much sense if they did as the grammar and syntax of the 2 languages differs quite a lot