[cmeng]

Yeah, I did this all as root. Could that be the problem... running XBMC as root?

Edit;
NM. The same issues occurs with a normal user.

Would it be possible to manually download the Tudou, Youku, and CCTV plugins from somewhere to see if they'll even work for this system?

Likely as mentioned by sciburst is due to file/directory access right. You can try to use
$ sudo chmod
$ sudo chown
commands to change the access rights of those required dirctories/files by xbmc to the login user's account and see it works.

I suppose direct copy the plugin will work, but then you have to do it every time there is a new update.