That's a preload tag
Modern browsers start downoading a video file before user presses 'play', as an optimization (like buffering)
Videos with preload="none" attribute should not be downloaded (and of course not played, also)
Maxthon (4.9 and 5.0) downloads immediatly all three videos in the page, before user clicks play in any of them, even if they are marked with preload="none"
You can check that from Developer tools, Network tab