ROFLS, ur vids crack me up
In reference to the your question:
Most of the larger YouTube Celebrities are straight up YouTube.
Or they make their own "company" that they host all of their own channels on (still through YouTube though)
That's not accurate. Most large Youtube channels (top 50) are partnered with a Network. Even RWJ is partnered (with Maker Studios). They usually get much better Ad deals with big Networks and overall support if you don't have a staff of your own.
If you click the Network names on Socialblade you can see their 50 most subscribed/viewed channels in their Network. It's quite interesting.
OT: I think Maker Studios (RPM & TGS) is my favorite Network just because a lot of my favorite channels are partnered with them and they are all very successful.