Ouch, well, all is not lost...
#1 rule
Do not add "stuff" manually
Now, if you access the Buffalo Terrastation does it have a folder structure like this
Public
User1
User2
etc?
If it does, move the media you want LMCE to see into the appropriate folder on the Terrastation (not on the Linux machine, those only contain shortcuts to the terrastation).
Move movies to
public/data/video
music to
public/data/audio
Now access the admin website for your LMCE install (just put in the IP of your LMCE box in the firefox address bar from any PC in the network).
Your username and password is the first LMCE user you put in.
Now select "configuration"->"devices" and see if you can find the terrastation as a file server under the Core (most likely)
Delete the device (not the Core, only the file server)
Now go into LMCE and confirm the device as usual when it finds it, select "file server" and "use LMCE folder structure"
Your media should pop up