you need an Ethernet Cable
If you are connecting to your ethernet port, You need a Crossover Cable
If your connecting through a hub, you need a standard Ethernet cable.
You then need to Download an FTP Prgram (Yummy FTP) for Mac and connect to the IP address of your xbox, (Found in Evolution X)
With the User Name: xbox
and password: xbox
You then copy your movies to either drive;
Any queries, dont be afraid to ask