But what you are not understanding is WATH gives you the license. They have a list of songs that you can use that they have the license for. You upload your video to WATH website. It enters their Content ID database. Then it gets set to your video you upload. You as the YouTube USER does not monetize it. The network monetizes it. YouTube sends a monthly report of earnings from all channels associated with Network. Then the Network pays the channels the split fee between YouTube user and publishers. Even Sony's Vice President confirmed this in an email I received from the. WATH has deals with Sony, Warner, Kobalt, Universal.
For the songs not listed on WATH the original publishers are what are claimed via Contend ID. You can either share in revenue with YouTube if publisher allow. The only way to never have a cover taken down is to use only the songs listed via WATH. Until YouTube has their own list of songs that clearly say "Monetizable for Covers" Then you don't know what you can upload.