Normally, Netflix has a CDN and when a customer views a video, that CDN serves the content --> which comes in through the ISP's providers --> costing the ISP bandwidth.
With OpenConnect, Netflix offers to give any major ISP that requests it, a free (or multiple free) OpenConnect devices. They are hands-off zero maintenance for the ISP, and they put them in the ISP's data centers.
This means, when a Netflix customers goes to view a video, it gets streamed off the OpenConnect appliance which is already inside the ISP's network -- and in-network traffic costs the ISP's almost nothing.
So, with OpenConnect, the ISP downloads a video once, then serves it up locally. Netflix customers get lower latency videos, and sometimes even higher HD content (overall better service), and ISP's get to reduce their traffic burden significantly, which saves them money.
This should be/is a win-win for everyone involved, the ISP, the mutual customer, and Netflix.
(the problem as we've seen through the net neutrality debate, the Big5 ISP's here in the US have all refused the OpenConnect appliances)