Originally Posted by GrouchyAdmin

You can do it quickly, but at the cost of CPU. Remember that Google runs on cheap, disposable hardware. It means nothing to them to tax a machine for 4 simultaneous streams. However, most of this industry can't afford that method. The only issue you have is that you want it to identify the video/image/etc to that specific user; and even at the very least, if you serve the file with the user's IP as a long2ip() encoded, that's not necessarily going to mean anything, as the file may be renamed. You need to embed it, and in order to do that, you almost always need to load the whole file into RAM to do so. Even with that, a realtime rewrite/passthru still takes a lot of effort.