Playing files from USB stick?

Hi all,

I’m considering buying the Broadcom Crystal HD card and installing it in my ATV. This means I will lose WiFi, but this is a problem as my router is downstairs which means I won’t be able to transfer files to my ATV from my Mac.

I’d like to know, is it possible to copy 1080p MKV files to a USB stick, stick it in the back of the ATV and then play them using XBMC/Boxee? If not I’ll have to buy myself an external HDD.