Your impression notwithstanding, the fact is that dozens of applications already exist that can play network streams, play files from your hdd, and even record streams to your hard disk (VLC for one), means that its a known solved problem. If, as you say, a video streaming app, at its core, cannot handle something so basic as saving the stream to disk, or playing the video from disk, then I would count that as a major design failure.
Also I don't get where the "undoubtedly", "fundamental change", "going to be easier to X" comes from. What is your basis for those statements?
