Here is an interview on a opposition Belarussian TV channel with an Ukrainian officer. One host is speaking Russian, the other speaks Belarussian and the guest speaks Ukrainian.
There is no translation, so I think they assume their target audience should understand. The guest seems to understand the Belarussian-speaking host. But for me, as a native Russian speaker, the interview is uncomprehensible.
So, I wonder whether Belarussians and Ukrainians understand each other better than Russians understand them?