Out of curiousity, I went and signed up for the Roku Developer SDK to see what would be involved... and in the forum, the first thing I see is your post and the reply about using the MP4 feeds...

 

It would be interesting to know what the optimal bitrate/resolution would be for the Roku, as our MP4 files are intended for portable devices and are probably much lower resolution than the device supports. If you can find specs, post them here...