Venya Pak is a native Russian speaker who speaks almost perfect, unaccented American English. Learners of English can watch his videos with no qualms and learn a lot. Как говорить на американском английском? - YouTube
On the other end of the spectrum is Graham Phillips, whose heavily English-accented Russian is practically unintelligible to me. Fortunately he’s trying to educate about Russia, not the Russian Language. - YouTube
One advantage that the non-native teacher has is the fact that he, too, had to learn the language at some point. He may be able to explain certain aspects that confuse the learner better than a native speaker who “just knows” and who may have trouble providing an explanation. On the other hand, I’ve seen videos of Russians teaching English where the instructor has heavily-accented English, and a few where the instructor makes minor mistakes.