I couldn't find my old login info from a few years ago. Went there this morning and there was a signup tab. Signed right up, verified email and was good to go.
If you want to upload your own videos you have to invited to do so.
It doesn't appear that many channels post regularly on Full30. Demolition Ranch hasn't posted since April, Mac hasn't posted since September. If you look at the list of All Channels, most of those don't show up under the recently uploaded going a few months back. When you can watch everything on youtube and not full30, it makes it hard to migrate over.
Guns are also far from the only thing I'm watching on Youtube as well. I'd venture to guess that would go for others as well.