@tekk pretty much covered it very well. The bit in 8 bit gaming systems refers to the graphics not audio.
But apparently the Nes did have sampling capabilities.
https://youtube.com/watch%3Fv%3Dla3coK5pq5w&sa=U&ved=0ahUKEwi25M-_-LHRAhUSxGMKHb8RBUoQtwIIEjAB&usg=AFQjCNElZ58Ji9g87S-ZorM1eZWkbRFCXw
Anyway, the sounds used for the bohemian rhapsody arrangement here remind me of the Sega genesis, a 16 bit system.
