Songs in the public domain are the only music you do not need to obtain special permission to use. However, copyright laws governing music composed before 1972 are at state discretion, so be absolutely certain a piece of music is in the public domain before using it as such in your YouTube video.
While this music is free to use, you still need to license it. Permission is usually very easy to get for using these songs, so there’s no point in trying to get around it. Take music copyright laws and YouTube seriously.
This is music that you must license from the copyright holder for and pay a fee to use, but it isn’t as involved as it sounds. There are many agencies that collect and disburse music royalties, making the process easier on everyone.
Beatstars.com is one that we recommend.
In most cases, making a cover song is simple. There is a government set rate for use of the song, but unfortunately this doesn’t cover transferring that music to video. You must obtain permission from the copyright holder to make a video of your cover legally.