A On Demand subscription doesn't entitle you to do a premix/ make your own workout and download it.
Once you have made a workout, you can play it using your internet connection, share it, modify it, delete but you can't extract it out of cathe OnDemand.
Basically you don't own any premix made on Cathe OnDemand.
Enabling any extraction of files would drop dvds sales , therefore increase subscriptions, IMHO.