I googled this question because I work for Time Warner and was telling my aunt about the feature using Roku with the Time Warner app. Thinking Comcast was superior to Time Warner, I just knew it was available up until we were on the phone with customer service a few minutes ago. Anyways to answer your question, if they do it like Time Warner, you have to have the cable and internet. It can recognize when your on your home network and will give you all the channels you subscribe to including OnDemand.
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