This might be more complexity than you are ready for, but here's what I suggest: * Remove the notion of two different modes. * Remove the ability to switch bet

This might be more complexity than you are ready for, but here's what I suggest: * Remove the notion of two different modes. * Remove the ability to switch between two modes. Because with this capability, people will inevitably switch it to the greedy mode, even if they have no need to, out of an inane fear that they might need to. * Implement your hybrid mode, again without a "switching" mechanism: * In your implementation of "rarest first", artificially apply extra weight to the next N segments that will be needed for the current play point. I think this will result in very good behavior, in all cases. It is completely hands-off. Users tight on bandwidth will inevitably spend all of their bandwidth downloading the extra weighted segments needed to place soon. Users with any spare bandwidth will easily get past the next and segments, and then the rarest segments will automatically be the next fetched. All without any switches for users to set wrong.