What is the spectrum-saving technology used to switch broadband cable channels on an 'as-needed' basis?

Switched Digital Video (SDV) is the correct answer because it is a technology that allows cable companies to manage their bandwidth efficiently by delivering video channels only when they are requested by viewers. Instead of broadcasting all channels to every subscriber, SDV switches channels on an 'as-needed' basis, significantly reducing the amount of bandwidth that is continuously used for channels that may not be actively watched.

This technique optimizes the available spectrum by allocating it dynamically, thereby enhancing the capacity for more HD channels and reducing network congestion during peak times. By using SDV, service providers can increase their video offerings and improve overall service quality for consumers, as it mitigates the limitations imposed by finite bandwidth resources.

The other options represent different technologies or services related to video streaming or bandwidth management, but they do not specifically address the 'as-needed' switching of broadband cable channels, which is the defining characteristic of Switched Digital Video.