I had a discussion not so long ago with someone who was convinced that a sync license was an absolute necessity for posting cover songs on YouTube. Though not mistaken, there is a legitimate workaround that offers a practical solution to the thousands of artists making cover videos. A Google search on the topic offers conflicting answers, so a bit of clarity on this subject can’t do any harm.
Firstly, let’s start with the strictly speaking, by-the-book angle: yes, a synchronization license or permission from the songwriters is required to publish your cover song video. Acquiring a sync license from the publisher of the composition allows you to pair your cover audio recording with your video. It doesn’t matter what type of visual content, it could be a music video or a clip of your cat doing tricks.
Now for the good news. YouTube’s Content ID system has changed the game by offering a workaround that allows you to publish to YouTube legally. The Content ID system analyses your upload to determine if contains any copyrighted content in your upload, and if so, places a claim on behalf of the publisher. In other words, the song is picked up by the Content ID system and YouTube follows the instructions of the copyright holders. In most cases the publisher will take over all monetization of your video, which means that any ad revenue generated by ads will be paid to the relevant rights holder. Publishing arrangements differ, so in some cases you may even be eligible for a share in the revenue. You'll know you can share in revenue from a cover song video when you see this message next to the video in your Monetization tab: “Monetize my video. This is my cover of a song written by somebody else. Learn more”.
Very rarely will the publisher instruct YouTube to take your video down. Remember, most publishers understand that monetizing cover song videos through YouTube can amount to real revenue, through no effort on their part. Apart from the added revenue stream, publishers have long realized that cover song videos generate added publicity, and in doing so add value to the catalogue that they represent. In other words: better to be making some money from artists who make cover videos than to spend time and money combating these videos that weren’t licensed through official channels.