--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -12171,16 +12171,33 @@ nsDocument::ApplyFullscreen(const Fullsc
   }
 
   // Dispatch "fullscreenchange" events. Note this loop is in reverse
   // order so that the events for the root document arrives before the leaf
   // document, as required by the spec.
   for (uint32_t i = 0; i < changed.Length(); ++i) {
     DispatchFullScreenChange(changed[changed.Length() - i - 1]);
   }
+
+  // If the element entering fullscreen is a video with controls,
+  // dispatch an independent event to the controls so that it won't
+  // need to listen on our normal fullscreenchange event.
+  if (elem->IsHTMLElement(nsGkAtoms::video) &&
+      elem->GetBoolAttr(nsGkAtoms::controls)) {
+    nsCOMPtr<nsINodeList> kids = elem->GetChildren(nsIContent::eAllChildren);
+    for (auto i : MakeRange(kids->Length())) {
+      nsIContent* item = kids->Item(i);
+      if (item->IsXULElement(nsGkAtoms::videocontrols)) {
+        DispatchCustomEventWithFlush(
+          item, NS_LITERAL_STRING("MediaEnteredFullscreen"),
+          /* Bubbles */ false, /* OnlyChrome */ false);
+        break;
+      }
+    }
+  }
   return true;
 }
 
 NS_IMETHODIMP
 nsDocument::GetMozFullScreenElement(nsIDOMElement **aFullScreenElement)
 {
   Element* el = GetFullscreenElement();
   nsCOMPtr<nsIDOMElement> retval = do_QueryInterface(el);

--- a/toolkit/content/widgets/videocontrols.xml
+++ b/toolkit/content/widgets/videocontrols.xml
@@ -1088,20 +1088,18 @@
                     this.fullscreenButton.setAttribute("aria-label", value);
 
                     if (this.isVideoInFullScreen())
                         this.fullscreenButton.setAttribute("fullscreened", "true");
                     else
                         this.fullscreenButton.removeAttribute("fullscreened");
                 },
 
-                onFullscreenChange: function () {
-                    if (this.isVideoInFullScreen()) {
-                        Utils._hideControlsTimeout = setTimeout(this._hideControlsFn, this.HIDE_CONTROLS_TIMEOUT_MS);
-                    }
+                onEnteredFullscreen: function () {
+                    Utils._hideControlsTimeout = setTimeout(this._hideControlsFn, this.HIDE_CONTROLS_TIMEOUT_MS);
                 },
 
                 clickToPlayClickHandler : function(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)
@@ -1519,17 +1517,17 @@
                     addListener(this.playButton, "command", this.togglePause);
                     addListener(this.fullscreenButton, "command", this.toggleFullscreen);
                     addListener(this.clickToPlay, "click", this.clickToPlayClickHandler);
                     addListener(this.controlsSpacer, "click", this.clickToPlayClickHandler);
                     addListener(this.controlsSpacer, "dblclick", this.toggleFullscreen);
 
                     addListener(this.videocontrols, "resizevideocontrols", this.adjustControlSize);
                     addListener(this.videocontrols, "transitionend", this.onTransitionEnd);
-                    addListener(this.video.ownerDocument, "mozfullscreenchange", this.onFullscreenChange);
+                    addListener(this.videocontrols, "MediaEnteredFullscreen", this.onEnteredFullscreen);
                     addListener(this.video, "keypress", this.keyHandler);
 
                     addListener(this.videocontrols, "dragstart", function(event) {
                         event.preventDefault(); //prevent dragging of controls image (bug 517114)
                     });
 
                     this.log("--- videocontrols initialized ---");
                 }