"On Demand" is dictated by when the user clicks the button or link to play the video. It has nothing to do with when you actually play it. You could set a timer for 10 minutes, but, it would boil down to, the surfer would see the video as a result of clicking on your link.
Something that may work, is to simply stop streaming. Zip the files up, and force the surfers to download and unzip the files before viewing.
