Fullscreen claims to have an ad sales team that have high paying ads. However, these ads will most likely serve channels with a lot of views and probably won't get any of these ads. Fullscreen will take 3o% of your money, so you will earn 30% less then if you had no networks. The reason why Fullscreen takes 30% is so they can give you features like a music library, a better dashboard, fourms, extra support, etc.