I have a large video file that I want to put on my main page. I don't want it to bog down the loading time, so I was thinking I could just set it to display:none and then change the display after the page loads. Would this work?
Would this work?
Nope. display: none will only prevent the element from being displayed; it will be loaded nevertheless.
You can watch this happen in the element inspector of your choice (e.g. in Firebug or IE8's dev tools).
The best way is probably to create the Video element using JavaScript afterwards, or - if you want a fail-safe solution in case JS is turned off - you could use an iframe that loads the video if the user clicks a link.
display has nothing to do with true speed of loading. However it may effect appearance of speed in the same way a splash page.
来源：https://stackoverflow.com/questions/4099637/does-displaynone-keep-elements-from-loading