Don't track `CGPGrey2` and `greysfavs`

[Pulling videos from **CGPGrey2** misrepresents Grey's video count](http://youtu.be/rMY0NgKXtCA?t=30s) since that channel doesn't contain any of his proper/educational videos.

This PR removes that as well as **greysfavs** so that the only videos of his that are counted are the ones on his primary channel.

/cc @nicktendo64