Mac OS X Movie/T.V artwork not downloading

Hi,

I bought my new mac mini today to use as a htpc, and was told that xmbc was the best way to organise my media.
Ive got all my films on my external hardrive in a movie folder. Im able to add the movies but it wont download any artwork. Ive spent most of the day on the internet watching videos, which do make it look easy, but no matter what i try nothing downloads.

All my films have been converted using subler to m4v so i can watch them on my ipad.


Any ideas??

Ive posted a video to show what im doing.






Thanks in advance and i hope ive put this in the right thread