Comcast brought video on-demand streaming to subscriber's mobile devices since early last year, but now an update has added the option to download (some) content for offline viewing. Arriving simultaneously on iOS and Android, the Xfinity TV Player apps support downloads from premium channels Showtime (which was also one of the first up for streaming when that launched), Starz, Encore and MoviePlex. We downloaded the app on both platforms and found it to work in similar fashion, assuming you're already logged in (and have any of those channels in your package) the option to download is right next to the usual stream button with options available for two different levels of picture quality. The high quality option wasn't quite HD quality to our eyes, but certainly passable for viewing on a flight or subway. We did run into a hiccup on Android however, with an "unknown error" stopping us from downloading files to our Galaxy S II running ICS. If there were more content available it would be a decent no-additional-hardware-needed matchup for solutions like TiVo's Stream or DirecTV's Nomad, while we wait for that you can get a taste of the apps for each platform at the source links.
Update:As of 11/20, Comcast pushed another update to the Android app, and after logging in again, we were able to download shows to our Galaxy S II without issue.
[Thanks to everyone who sent this in]