Proliferation of increasingly narrower genres aka Thomas the Tank Engine does Queen

I recently introduced my boys to Youtube. Sheer foolishness on my part I know, as now I get pestered.

But what has struck me is the development of genres and subgenres within Youtube, I assume becasue of its capacity to reach such a broad base of people.

My boys have a liking for the Thomas the Tank engine genre. Within that I have dicovered subgenres such as what I call Tommypop, thomas images set to a familiar pop/rock song and Tommycam, re-enactments of TTE stories (or sometimes original) using TTE toys. I have included an example of Tommypop above (with a song by Queen - can you guess?)