A legitimate firefox bug?<p>Firefox did this for me too, so I started investigating the glitch.  Chrome worked just fine.   Overall, this sort of thing would happen to me occasionally (and my colleagues) with h.264 &lt;video&gt; elements: it&#x27;s some kind of a freaky and infuriating bug.  I can&#x27;t explain it, but I suspected the actual problem was with the original network transmission and a client-side caching mechanism, possibly aggravated by server-side caching mechanisms.  Reason why I thought that is below, but now I&#x27;m not so sure: I copied that Earth video to a private server and it froze at the same exact spot, albeit it got less frames parsed&#x2F;decoded&#x2F;presented&#x2F;painted than I put below during the S3 render.<p>Last project I was working on had MP4 files (h.264 encoded) hosted on an iron server, with varnish-cache configured for streaming (streaming config was an attempt to troubleshoot the glitch.)  During the development I must have previewed the work-in-progress hundreds of times so I initially chalked the behavior up to caching freaking out.  After resetting cache manually or pulling up the file and shift-refreshing, things would work fine for awhile.  Attempting to reset cache doesn&#x27;t fix the stalled Earth video.<p>The video files I was previously working with were 2-4 mb in size, nearly as &#x27;small&#x27; as some larger higher quality images, so I don&#x27;t think filesize triggered the issue.  The ultimate fix for my project was to superstitiously switch from directly-hosting MP4 files to move them to akamai&#x27;s CDN because that had worked in the past without an observed glitch.  I can&#x27;t explain why this eliminated the problem, but it did (or I just stopped looking at the project): I imagine akamai has a whole bag of tricks up their sleeves, and at that point I was so done with the problem that I didn&#x27;t care.<p>That is, I didn&#x27;t care until I saw this glitch again just hours ago and realized it wasn&#x27;t just me and my shoddy work that made it happen.  So, I pulled up the direct MP4 video of this earth loop (hosted on S3), and pulled up stats for it (right click on video menu).  The video was supposed to be 12 seconds long, but it only loaded about 2, letting me see same thing you did before the playback froze.  The video stats read the following:<p><pre><code>    Media:            2015-08-03.mp4
    Size:             2200x2200 scaled to 1085x1085
    Activity:         Ended
    Volume:           100%
    readyState:       HAVE_CURRENT_DATA
    networkState:     NETWORK_IDLE
    Frames parsed:    2030
    Frames decoded:   1696
    Frames presented: 189
    Frames painted:   168
</code></pre>
Despite this info dump, firebug revealed (or claimed) that around 32 MB of the file was transmitted.  I hit play and the video stopped at 2 seconds.  ffprobe claims that nb_frames is 278 (24 * 11.583333), rounded up.  So where the heck are the other 89 frames, firefox??  When copying this video to my slower private server, even fewer frames were presented&#x2F;painted.<p>Any firefox devs around?