You really do not need to join an MCN, as a matter of fact you are paying them for their services in my eyes. I look at what an MCN's service has to offer me more than what I can already do and the smaller one's really don't offer you that much. What's the point of giving us useless apps which let's face it you don't need to use at all and can manage without them. Smaller MCN's especially tell you that they will promote you on their youtube/social media platform but a lot of them don't have that many followers or subscribers so you may not notice a huge increase in subs or viewers doing this. The MCN I am with which is Aultra is quite new and because I barely make money from my YT I might as well try it out and let other people know since it's a no lock in contract and because I understand UK law and contract law especially when they state in their contract and their dashboard is a no lock in and takes x days to take care of I can sue them If they don't let me go when I want to. The only reason I joined an MCN is so I don't have to bother with legal jargon like claims etc because some MCN's do support you on this by taking care of those false claims and they also can file claims under your name if people steal your content or they can also file a third party match so you can make money from people who steal your content if you wish for them to keep the video up. I'm just happy to be under an MCN so any issues with my channel can be resolved by them especially if they can use the correct terminology against people and just deal with any problems in a professional manner (which not all of them may do, not even sure If my MCN can do that since the person who got in touch with me was not really professional at all). I have noticed an increase In my revenue but that's very hard to measure since I could just be having a lucky week. But for the CPM promise they told me this (quoting the employee) "We promote you on sites we get in contact with youtube to help with your videos being seen faster and easier by people on youtube" but from listening to people's experience some people say it is a straight lie which I believe it is a lie since adwords (Google) deals with ad revenue CPM also they have a sales team for it not the MCN and we have big YouTubers like Onision who also say that they lie and cannot get you higher CPM's. I also suggest reading
this since it is a good read and I don't believe Networks are there to earn you more money to me they are good if you want to keep your content safe from being re-uploaded or dealing with claims, some can also get you partnerships and sponsorships, that is the way I see it. Also the networks that let everyone in cannot possibly manage all the accounts either so I do believe a lot of them make fake promises as they just cannot have that many employee's working under them.
