You should still be easily able to do that unless I am missunderstanding you. You need to enable CIFS on the NAS (under “standard file protocols” in your UI), which is seen by windows boxes as SAMBA. Then share the folders that your movies are in. I do not have a ReadyNas so cannot confirm that this works with the HUB this way, but I don’t see why not. CIFS is similar to SAMBA with a few enhancements and is a native Windows protocol. The HUB should see the NAS’ shares like they were on a PC, and work fine with the theme.
Once setup, if you can see the shares from a PC (assuming you have one), then you should be off and running on the HUB. This is speculation on my part as I am using straight SAMBA not CIFS, so perhaps someone running that on their NAS can confirm as well.
Let us know how it works. It would be a good thing to know.