The Miley Cyrus videos are most likely licensed as well. It's really not difficult for record companies to take this stuff down if they want to: hire an intern

The Miley Cyrus videos are most likely licensed as well. It's really not difficult for record companies to take this stuff down if they want to: hire an intern at $8/hr to do searches for your top 50 artists and report the videos to youtube (they are pretty damn responsive). Bam, problem solved for < $30k a year. If the intern can't find the stuff it's not going to be doing much harm.