That's because there is so much variation in what you watch on youtube - from listening to music, to movie trailers, to sports highlights, to howtos about cooki

That's because there is so much variation in what you watch on youtube - from listening to music, to movie trailers, to sports highlights, to howtos about cooking, etc. The music we listen to is way easier to analyse, even if we have some variation in what we like. Sometimes im in the mood for classical, sometimes its rap. Easy to differentiate and offer me playlists for each genre.