Prevent HTML5 videos from downloading the files on mobile - videojs

One way you could do this is by setting the src attributes of your video element via JavaScript, and only doing so based on a media query (using matchMedia).

This would mean that the bulk of your code would have to move to JavaScript though.

For example, your HTML could be something like:

<video data-mp4="video.mp4" data-webm="video.webm" class="video-js" controls></video>

And then in your JavaScript (pseudo code here, not actual JS):

if (window.matchMedia("(min-width: 640px)").matches) {
   // do nothing
} else {
   var videos = document.querySelectorAll('.video-js'),
       videoFile;
   for (var i = 0; i < videos.length; i++) {
      // Choose video type
      if (video[i].canPlayType("video/mp4") === "probably") {
         videoFile = video[i].getAttribute("data-mp4");
      }
      // do the same check for WebM here...
      video[i].src = videoFile;
      // Call whatever reload or refresh method video.js has
      // for example...
      video[i].refresh();
   }
}

Something like that might work for you, although you might have to play around a bit with it.

Based on the suggestions Ian kindly made, here is my working solution.

Firstly, I changed each video's child source elements to have an attribute data-src like so:

<video id="my-id">    
   <source data-src="somevideo.mp4">
</video>

Then, after performing a mobile check using the script available at http://detectmobilebrowsers.com/ which I modified to include iPads etc (related SO answer here) I simply used the following script to automatically update the src attribute of each video (if we're on desktop in my case):

var sources = document.querySelectorAll('video#my-id source');
// Define the video object this source is contained inside
var video = document.querySelector('video#my-id');
for(var i = 0; i<sources.length;i++) {
  sources[i].setAttribute('src', sources[i].getAttribute('data-src'));
}
// If for some reason we do want to load the video after, for desktop as opposed to mobile (I'd imagine), use videojs API to load
video.load(); 

And that's it! Nothing loads on mobile devices anymore and I can have fairly granular control over the devices it will or won't load on.

Hope this helps somebody.

Based on Ian and GDGR's answers, I modified this to work for multiple videos.

<video class="mobile-no-load">    
    <source data-src="somevideo.mp4">
 </video>

if (window.innerWidth > 730) {   
    // get multiple videos
    var sources = document.querySelectorAll('video.mobile-no-load'); 
    // loop through the videos
    sources.forEach(function(source){ 
        // target the src attribute of the <source> element and set it to the data-src attribute
        source.childNodes[1].setAttribute('src', source.childNodes[1].getAttribute('data-src'))
    }); 
}