Streaming is nothing more than opening a file and processing the resultant stream(!) of data.

Whether you grab your MP3 off of local storage (eg: HDD), off of LAN storage (eg: NAS), or off of WAN storage (eg: Youtube), you're streaming.

When anyone talks about streaming music or video they are talking about downloading it as they're watching it. You are hallucinating a definition that no one uses. Try to understand the context if you can.