serve HTML5 mp4 video headers being cancelled

Question

I am trying to serve a video file. I got it working for the flash version however I want it to work on mobile devices using HTML5 video tag. I am using JWPlayer for the video player.

I saw this solution from mobiforge.com and implemented it. Now it has helped me get it semi working and as it seems the correct headers are sent but not every page load, I have had to refresh it a couple times for the correct headers to appear. Also the request gets cancelled after downloading around 1.66MB of the video file. then the video says the error.

The video could not be loaded, either because the server or network failed or
because the format is not supported: