get dynamicControls() {
                   // Don't fade controls for <audio> elements.
                   var enabled = !this.isAudioOnly;

                   // Allow tests to explicitly suppress the fading of controls.
                   if (this.video.hasAttribute("mozNoDynamicControls"))
                       enabled = false;

                   // If the video hits an error, suppress controls if it
                   // hasn't managed to do anything else yet.
                   if (!this.firstFrameShown && (this.video.error || this.video.networkState == this.video.NETWORK_NO_SOURCE))
                       enabled = false;

                   return enabled;
               },

Ok, evidently this just happened over night. I don't know what is going on, and after googling for hours, i'm not finding anyone else with the SAME issue. My site uses the webm video and audio format. Today i woke up to find that it was no longer working*. Here's what's going on: Example video: http://thesocialexpo.com/?a=SMMM_Multimedia_Display&id=12984049790379189 Browser: Firefox: The video will play, if you right click and select "play", but the video CONTROLS do not show up, unless you tell the video to go wide or full screen. If you mouseover the video element, you can see javascript errors in firefox's chrome module for the video element. The error is: Error: this.video is null Source File: chrome://global/content/bindings/videocontrols.xml Line: 394 In the chrome component for the video element, that block of code is: get dynamicControls() { // Don't fade controls for <audio> elements. var enabled = !this.isAudioOnly; // Allow tests to explicitly suppress the fading of controls. if (this.video.hasAttribute("mozNoDynamicControls")) enabled = false; // If the video hits an error, suppress controls if it // hasn't managed to do anything else yet. if (!this.firstFrameShown && (this.video.error || this.video.networkState == this.video.NETWORK_NO_SOURCE)) enabled = false; return enabled; }, Browser: Chrome: The video player's controls show up, but it will not play AT ALL. Browser: Opera: Everything is fine. Browser: Firefox on Windows: Everything is fine. The firefox build that i'm using is from the Remi repo. I have done NO updates of my system in about a week, so that can't be it, as this was FINE yesterday. My server is returning the correct mime type. I've rebooted my server, just in case, and it made no difference. I've also checked out other webm video examples on the internet, and it seems like they won't play at all in firefox suddenly, but SOME of them DO play in chrome. Chrome on windows: controls show up, but video doesn't work at all.