--- a/toolkit/content/widgets/videocontrols.xml
+++ b/toolkit/content/widgets/videocontrols.xml
@@ -1229,22 +1229,47 @@
         if (this.isVideoInFullScreen()) {
           this.fullscreenButton.setAttribute("fullscreened", "true");
         } else {
           this.fullscreenButton.removeAttribute("fullscreened");
         }
       },
 
       onFullscreenChange() {
+        this.updateOrientationState(this.isVideoInFullScreen());
         if (this.isVideoInFullScreen()) {
           Utils._hideControlsTimeout = setTimeout(this._hideControlsFn, this.HIDE_CONTROLS_TIMEOUT_MS);
         }
         this.setFullscreenButtonState();
       },
 
+      updateOrientationState(lock) {
+        if (!this.video.mozOrientationLockEnabled) {
+          return;
+        }
+        if (lock) {
+          if (this.video.mozIsOrientationLocked) {
+            return;
+          }
+          let dimenDiff = this.video.videoWidth - this.video.videoHeight;
+          if (dimenDiff > 0) {
+            this.video.mozIsOrientationLocked = window.screen.mozLockOrientation("landscape");
+          } else if (dimenDiff < 0) {
+            this.video.mozIsOrientationLocked = window.screen.mozLockOrientation("portrait");
+          } else {
+            this.video.mozIsOrientationLocked = window.screen.mozLockOrientation(window.screen.orientation);
+          }
+        } else {
+          if (this.video.mozIsOrientationLocked) {
+            window.screen.mozUnlockOrientation();
+            this.video.mozIsOrientationLocked = false;
+          }
+        }
+      },
+
       clickToPlayClickHandler(e) {
         if (e.button != 0) {
           return;
         }
         if (this.hasError() && !this.suppressError) {
           // Errors that can be dismissed should be placed here as we discover them.
           if (this.video.error.code != this.video.error.MEDIA_ERR_ABORTED) {
             return;
@@ -1831,16 +1856,17 @@
     };
 
     this.Utils.init(this);
     ]]>
   </constructor>
   <destructor>
     <![CDATA[
     this.Utils.terminateEventListeners();
+    this.Utils.updateOrientationState(false);
     // randomID used to be a <field>, which meant that the XBL machinery
     // undefined the property when the element was unbound. The code in
     // this file actually depends on this, so now that randomID is an
     // expando, we need to make sure to explicitly delete it.
     delete this.randomID;
     ]]>
   </destructor>