Congrats! But why do people apply to stuff like Fullscreen instead of the traditional method?
A very good question and the answers you will get are as multifarious as the different colors of an kaleidoscope.
A few Years ago it doesn`t need much to get famous or reach an bigger audience on YouTube. After Google did took YouTube over in 2006 it did change the hole Business a lot in the last couple of Years and you nowadays see literally every Day like Millions of new Comedian, Let`s Play, Prank, Singer, Songwriter,... Channels going on Air that try to gain some Views or try to become the next Justin Bieber/Ray William Johnson/Smosh/Paris Hilton Makeup Doll/...
While YouTube itself had allowed in the first Years almost everyone to get the Benefits of an YouTube Partner Account (I`m not talking about the Money Part!) when you had reached some Level of Fame/Audience oriented Content Google did exactly the opposite a few Years long and is now badly trying to change it back to what it was when everyone didn´t cared about the Money in first Place and more about the Content itself.
The Way Google worked from 2006 - 2012:
If you don`t create something that does generate revenues in whatever Way it does YouTube/Google will never ever give you any Benefits of an YouTube Partner Account.
So when it's all about the Money, doesn't that usually, you know, attract those that already have much and want even more?
While at the Beginning it were mostly just People like you and me that were trying to have some fun and share something with everyone else that didn`t saw the Money as their Main Goal starting with 2008/2009 Multi-Million Dollar Companies joined the YouTube Rumble and since then a lot has changed. Some of the biggest YouTube Celebs of the last 3.4 Years were made. If you would take the time and take a look who had generate the most Incoming in 2011 you would realize that almost half of them weren`t just some normal YouTuber who had start at Zero. If you dig deep enough you might find some surprises you won`t usually read in the Rainbow Press or in the Times/Forbes
What does that have to do with Networks like Fullscreen, TGN, Machinima?
Those Networks have actually the Power to give you that what YouTube itself did in the first Years and stopped after YouTube were bought by Google. They can give you the Benefits of an YouTube Partnership Program while still not being a YouTube Superstar or being some Celeb who simple can buy those Feature.
As the YouTube Partner Program itself isn`t still available everywhere where you would expect it to be, even if in April the YouTube PR had literally tried to make it look like it`s that Way when you had read almost everywhere "YouTube Partner Program Opens To All" or "YouTube Opens Partner Program to Everyone" it actually wasn`t the full truth.
As far as I know the YouTube Partner program is currently available in...
Argentina, Australia, Brazil, Canada, Colombia, Czech Republic, France, Germany, Ireland, Israel, Japan, Mexico, Netherlands, New Zealand, Poland, South Africa, Spain, Sweden, United Kingdom and the United States.
Hey, that like 20 Country - what`s with the other 250+ that are Worldwide on our little Planet?
And that`s exactly where those Networks mentioned above jump in. Even if you are not from one of those twenty Country those Network are able to upgrade your Account to to something very similar to an YouTube Partnership Account with almost all it`s Benefits in less then a few Hours even if YouTube told you that they won`t add you to the YouTube Partnership Program on their own after you have applied for it.
So to come to an End...
Most are joining those Networks because they didn`t get enough Views, generate enough revenues so YouTube offers them a YouTube Partnership Account or as simple as can`t ever become a Member of that Program since YouTube doesn`t offer it at their Place.