--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -1305,32 +1305,56 @@ MediaDecoder::NotifyCompositor()
   }
 }
 
 void
 MediaDecoder::SetElementVisibility(bool aIsVisible)
 {
   MOZ_ASSERT(NS_IsMainThread());
   mElementVisible = aIsVisible;
-  mIsVisible = !mForcedHidden && mElementVisible;
+  UpdateVideoDecodeMode();
 }
 
 void
 MediaDecoder::SetForcedHidden(bool aForcedHidden)
 {
   MOZ_ASSERT(NS_IsMainThread());
   mForcedHidden = aForcedHidden;
-  SetElementVisibility(mElementVisible);
+  UpdateVideoDecodeMode();
 }
 
 void
 MediaDecoder::SetSuspendTaint(bool aTainted)
 {
   MOZ_ASSERT(NS_IsMainThread());
   mHasSuspendTaint = aTainted;
+  UpdateVideoDecodeMode();
+}
+
+void
+MediaDecoder::UpdateVideoDecodeMode()
+{
+  // The MDSM may yet be set.
+  if (!mDecoderStateMachine) {
+    return;
+  }
+
+  // If mHasSuspendTaint is set, never suspend the video decoder.
+  if (mHasSuspendTaint) {
+    mDecoderStateMachine->SetVideoDecodeMode(VideoDecodeMode::Normal);
+    return;
+  }
+
+  // If mForcedHidden is set, suspend the video decoder anyway.
+  // Otherwise, depends on the owner's visibility state.
+  if (!mForcedHidden && mElementVisible) {
+    mDecoderStateMachine->SetVideoDecodeMode(VideoDecodeMode::Normal);
+  } else {
+    mDecoderStateMachine->SetVideoDecodeMode(VideoDecodeMode::Suspend);
+  }
 }
 
 bool
 MediaDecoder::HasSuspendTaint() const
 {
   MOZ_ASSERT(NS_IsMainThread());
   return mHasSuspendTaint;
 }
@@ -1499,16 +1523,17 @@ MediaDecoder::DisconnectMirrors()
 void
 MediaDecoder::SetStateMachine(MediaDecoderStateMachine* aStateMachine)
 {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT_IF(aStateMachine, !mDecoderStateMachine);
   mDecoderStateMachine = aStateMachine;
   if (aStateMachine) {
     ConnectMirrors(aStateMachine);
+    UpdateVideoDecodeMode();
   } else {
     DisconnectMirrors();
   }
 }
 
 ImageContainer*
 MediaDecoder::GetImageContainer()
 {

--- a/dom/media/MediaDecoder.h
+++ b/dom/media/MediaDecoder.h
@@ -378,16 +378,18 @@ private:
   void SetForcedHidden(bool aForcedHidden);
 
   // Mark the decoder as tainted, meaning suspend-video-decoder is disabled.
   void SetSuspendTaint(bool aTaint);
 
   // Returns true if the decoder can't participate in suspend-video-decoder.
   bool HasSuspendTaint() const;
 
+  void UpdateVideoDecodeMode();
+
   /******
    * The following methods must only be called on the main
    * thread.
    ******/
 
   // Change to a new play state. This updates the mState variable and
   // notifies any thread blocking on this object's monitor of the
   // change. Call on the main thread only.