Before I got rid of it, I used my Roku Netflix Player to playback recorded tv from MythTV. Here’s the app and a couple videos showing how it looked.
Here’s a link to Roku’s Developer site
Here’s a link to the zip containing the demo video player. I’ve made a few modifications so it loads a demo video from this site.
To use it, modify conn.UrlPrefix in categoryFeed.brs in the source folder and rezip and upload to the roku device.