Much like the way Repost operates on SoundCloud, YouTube MCNs are third-party service providers that help creators monetize the original content on their YouTube channels. These businesses aggregate multiple YouTube channels and offer services that may include audience development, content programming, creator collaborations, digital rights management, monetization, and/or sales, brand opportunities, and more. Thus the name Multi-Channel Network (i.e. MCN)
The main purpose of an MCN is to provide value to your channel and your brand. This can come in a variety of different forms, from design assets to overall production resources for your videos or your songs (equipment, studios, funding, etc.). In exchange for these services they will also take a percentage of all the money that your channel makes on Ad Revenue, similar to the way a record label or publisher might take a percentage of your distribution/publishing for investing in your production.
That being the case, when you join an MCN, all of your revenue will immediately begin to flow through your MCN’s AdSense account. Your MCN will also have access to your YouTube Analytics revenue data. Presumably, this allows the artist to focus entirely on their work, while the MCN handles all of the administrative tasks behind the scenes. Some MCNs also offer additional revenue opportunities, such as brand sponsorships or dedicated sales teams that may contribute to higher overall earnings for your channel. If a network offers you these services, you may wish to make sure they are specified in your contract. Overall, MCNs can be a very powerful asset to your production and brand as an artist. But before you sign a contract you want to be sure you know exactly how much they are planning to give and exactly how much they are planning to take in return, so you can make sure to find exactly the right fit for you!