--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -10270,16 +10270,32 @@ nsDocument::AddResponsiveContent(nsICont
 void
 nsDocument::RemoveResponsiveContent(nsIContent* aContent)
 {
   MOZ_ASSERT(aContent);
   mResponsiveContent.RemoveEntry(aContent);
 }
 
 void
+nsDocument::AddMediaContent(nsIContent* aContent)
+{
+  MOZ_ASSERT(aContent);
+  MOZ_ASSERT(aContent->IsHTMLElement(nsGkAtoms::video) ||
+             aContent->IsHTMLElement(nsGkAtoms::audio));
+  mMediaContent.PutEntry(aContent);
+}
+
+void
+nsDocument::RemoveMediaContent(nsIContent* aContent)
+{
+  MOZ_ASSERT(aContent);
+  mMediaContent.RemoveEntry(aContent);
+}
+
+void
 nsDocument::NotifyMediaFeatureValuesChanged()
 {
   for (auto iter = mResponsiveContent.ConstIter(); !iter.Done();
        iter.Next()) {
     nsCOMPtr<nsIContent> content = iter.Get()->GetKey();
     if (content->IsHTMLElement(nsGkAtoms::img)) {
       auto* imageElement = static_cast<HTMLImageElement*>(content.get());
       imageElement->MediaFeatureValuesChanged();
@@ -12070,16 +12086,20 @@ nsDocument::MaybeActiveMediaComponents()
   if (mEverInForeground) {
     return;
   }
 
   if (!mWindow) {
     return;
   }
 
+  if (mMediaContent.IsEmpty()) {
+    return;
+  }
+
   mEverInForeground = true;
   GetWindow()->MaybeActiveMediaComponents();
 }
 
 NS_IMETHODIMP
 nsDocument::GetHidden(bool* aHidden)
 {
   *aHidden = Hidden();

--- a/dom/base/nsDocument.h
+++ b/dom/base/nsDocument.h
@@ -1006,16 +1006,23 @@ public:
   virtual nsresult AddResponsiveContent(nsIContent* aContent) override;
   // Removes an element from mResponsiveContent when the element is
   // removed from the tree.
   virtual void RemoveResponsiveContent(nsIContent* aContent) override;
   // Notifies any responsive content added by AddResponsiveContent upon media
   // features values changing.
   virtual void NotifyMediaFeatureValuesChanged() override;
 
+  // Adds an element to mMediaContent when the element is added to the tree.
+  virtual void AddMediaContent(nsIContent* aContent) override;
+
+  // Removes an element from mMediaContent when the element is removed from
+  // the tree.
+  virtual void RemoveMediaContent(nsIContent* aContent) override;
+
   virtual nsresult GetStateObject(nsIVariant** aResult) override;
 
   virtual nsDOMNavigationTiming* GetNavigationTiming() const override;
   virtual nsresult SetNavigationTiming(nsDOMNavigationTiming* aTiming) override;
 
   virtual Element* FindImageMap(const nsAString& aNormalizedMapName) override;
 
   virtual nsTArray<Element*> GetFullscreenStack() const override;
@@ -1553,16 +1560,19 @@ private:
   // state so we can provide useful assertions to consumers of ForgetLink and
   // AddStyleRelevantLink.
   bool mStyledLinksCleared;
 #endif
 
   // A set of responsive images keyed by address pointer.
   nsTHashtable< nsPtrHashKey<nsIContent> > mResponsiveContent;
 
+  // A set of media elements keyed by address pointer.
+  nsTHashtable<nsPtrHashKey<nsIContent>> mMediaContent;
+
   // Member to store out last-selected stylesheet set.
   nsString mLastStyleSheetSet;
 
   nsTArray<RefPtr<nsFrameLoader> > mInitializableFrameLoaders;
   nsTArray<nsCOMPtr<nsIRunnable> > mFrameLoaderFinalizers;
   RefPtr<nsRunnableMethod<nsDocument> > mFrameLoaderRunner;
 
   nsCOMPtr<nsIRunnable> mMaybeEndOutermostXBLUpdateRunner;

--- a/dom/base/nsIDocument.h
+++ b/dom/base/nsIDocument.h
@@ -2428,16 +2428,19 @@ public:
   virtual nsresult AddPlugin(nsIObjectLoadingContent* aPlugin) = 0;
   virtual void RemovePlugin(nsIObjectLoadingContent* aPlugin) = 0;
   virtual void GetPlugins(nsTArray<nsIObjectLoadingContent*>& aPlugins) = 0;
 
   virtual nsresult AddResponsiveContent(nsIContent* aContent) = 0;
   virtual void RemoveResponsiveContent(nsIContent* aContent) = 0;
   virtual void NotifyMediaFeatureValuesChanged() = 0;
 
+  virtual void AddMediaContent(nsIContent* aContent) = 0;
+  virtual void RemoveMediaContent(nsIContent* aContent) = 0;
+
   virtual nsresult GetStateObject(nsIVariant** aResult) = 0;
 
   virtual nsDOMNavigationTiming* GetNavigationTiming() const = 0;
 
   virtual nsresult SetNavigationTiming(nsDOMNavigationTiming* aTiming) = 0;
 
   virtual Element* FindImageMap(const nsAString& aNormalizedMapName) = 0;
 

--- a/dom/html/HTMLMediaElement.cpp
+++ b/dom/html/HTMLMediaElement.cpp
@@ -4274,16 +4274,17 @@ nsresult HTMLMediaElement::BindToTree(ns
 
   if (aDocument) {
     mAutoplayEnabled =
       IsAutoplayEnabled() && (!aDocument || !aDocument->IsStaticDocument()) &&
       !IsEditable();
     // The preload action depends on the value of the autoplay attribute.
     // It's value may have changed, so update it.
     UpdatePreloadAction();
+    aDocument->AddMediaContent(this);
   }
 
   if (mDecoder) {
     // When the MediaElement is binding to tree, the dormant status is
     // aligned to document's hidden status.
     mDecoder->NotifyOwnerActivityChanged(!IsHidden());
   }
 
@@ -4509,16 +4510,19 @@ HTMLMediaElement::ReportTelemetry()
     }
   }
 }
 
 void HTMLMediaElement::UnbindFromTree(bool aDeep,
                                       bool aNullParent)
 {
   mUnboundFromTree = true;
+  if (OwnerDoc()) {
+    OwnerDoc()->RemoveMediaContent(this);
+  }
 
   nsGenericHTMLElement::UnbindFromTree(aDeep, aNullParent);
 
   if (mDecoder) {
     MOZ_ASSERT(IsHidden());
     mDecoder->NotifyOwnerActivityChanged(false);
   }