Download video file if it doesn't exist in the directory once it's requested

[xilve]

I want to be able to have users play a video file as they're downloading it. I know that streaming has been around for a long time, however if the file doesn't exist in the directory is it possible for me to download it and play it for the user at the same time. Here's how it goes:User clicks on file movie1.mp4 which is supposedly located at /videos/movie1.mp4However, in the directory videos, no such file exists. But, in directory /videos2/movie1.mp4 does exist.Is it possible for me to download movie1.mp4 from directory /videos2 while playing it as if it's located in directory /videos I hope what I've said above makes sense, if not please tell me so that I can provide more info.