Suggestions for Setup

What’s the best approach to storing iTunes content externally while avoiding the need to run a computer, ipad, or some other device (aside from a NAS or external HD) when I want to play my purchased iTunes movies?  I have a DNS-325 NAS, and an ICYDOCK dual bay HD - but it seems the best solution for what I want is to simply buy one of the time capsules and use the external HD’s to back up the time capsule data.  The only other option is to use one of my external HD’s and get an airport extreme.  I don’t use the ATV2 for music since I stream all of my content via a Sonos setup.  I also don’t own any non-iTunes media. 

If I go the above route, do I even need ATV Flash installed?