ITV2 probably push on-demand more because that target market, 16-34 is more likely to be using it or know about it, plus I dare say its probably more of a reliable way to track exactly what's being watched and when its being watched as opposed to tracking viewers through the traditional BARB system. BBC iPlayer for example reported an episode of Peter Kay's Car Share racked up 2.4m viewers on the BBC iPlayer alone excluding Virgin/Sky requests. Add in requests from Sky and Virgin and whatever else, that's probably another quarter of a million catch-up views for that show.
I use on-demand and catchup on ITV2 shows like 'American Dad!' and some ITV shows like 'Cold Feet'.
Part of the ITV Network, This is Granada. At 6.30pm