You are right, but it should be added that "prawilny" is used as a slang for "good guy" among some young people subcultures. It's no longer used much.

There's certainly a number of Russian words in older Warsaw slang (barachło, ustrojstwo, wierchuszka, etc.), but the videos were not using slang, especially not older slang, and they had no reason to use prawilny except by accident.