Youtube costs two million dollars a day to run. If you are planning on hosting music, better sites like www.grooveshark.com already exist. Furthermore, everyone is fine with uploading their audio files to Youtube. All the lectures I listen to are through iTunes U along with all other audio files. Indie bands can distribute their music through iTunes using sites like www.cdbaby.com.

The url is horrible.

You want to be Youtube for lectures and music and have a social media aspect and be last.fm with a radio functionality and twitter integration. Your idea is too broad.

Apologies for being overtly negative. You seem to have your idea thought out so I thought I'd give you some perspective.