For the moment, only country top are stored to REDIS for 24 hours. Search history and other user data are loaded once at startup and given by MySQL. The call to external APIs (to search, to retrieve playlist and so on) are made directy through your browser. (thanks to JSONP) :)
Youtube's recommendation list sucks. They only auto-play your lists not their recommendation lists. That sucks even more.
It will be great if you can add channels like house music, electronic, trans etc then you can pose threat to Spotify :-)
I had same idea as your's but for android. My friends disagreed with me saying it won't work but I will still do it :-)
We can use youtube as a database to create great interfaces which suck less to listen to music in pain less ways.
Would you mind sharing your tech stack?
Again, great job. Execution done with brilliance