diff --git a/dom/media/MediaDataDemuxer.h b/dom/media/MediaDataDemuxer.h
index aa9bf6e674b9..79ef5f5f0a05 100644
--- a/dom/media/MediaDataDemuxer.h
+++ b/dom/media/MediaDataDemuxer.h
@@ -35,7 +35,7 @@ class MediaDataDemuxer : public DecoderDoctorLifeLogger<MediaDataDemuxer> {
  public:
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaDataDemuxer)
 
-  typedef MozPromise<MediaResult, MediaResult, /* IsExclusive = */ true>
+  typedef MozPromise<MediaResult, MediaResult, /* IsExclusive = */ false>
       InitPromise;
 
   // Initializes the demuxer. Other methods cannot be called unless
diff --git a/dom/media/MediaDecoder.cpp b/dom/media/MediaDecoder.cpp
index 7f2b2b0970b1..397854406cf2 100644
--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -436,12 +436,13 @@ void MediaDecoder::OnPlaybackErrorEvent(const MediaResult& aError) {
     return;
   }
 
-  // External engine can't play the resource, try to use our own state machine
-  // again. Here we will create a new state machine immediately and asynchrously
-  // shutdown the old one because we don't want to dispatch any task to the old
-  // state machine. Therefore, we will disconnect anything related with the old
-  // state machine, create a new state machine and setup events/mirror/etc, then
-  // shutdown the old one and release its reference once it finishes shutdown.
+  // External engine can't play the resource or we intentionally disable it, try
+  // to use our own state machine again. Here we will create a new state machine
+  // immediately and asynchrously shutdown the old one because we don't want to
+  // dispatch any task to the old state machine. Therefore, we will disconnect
+  // anything related with the old state machine, create a new state machine and
+  // setup events/mirror/etc, then shutdown the old one and release its
+  // reference once it finishes shutdown.
   MOZ_ASSERT(aError == NS_ERROR_DOM_MEDIA_EXTERNAL_ENGINE_NOT_SUPPORTED_ERR);
   RefPtr<MediaDecoderStateMachineBase> discardStateMachine =
       mDecoderStateMachine;
@@ -1369,6 +1370,16 @@ bool MediaDecoder::CanPlayThrough() {
 
 RefPtr<SetCDMPromise> MediaDecoder::SetCDMProxy(CDMProxy* aProxy) {
   MOZ_ASSERT(NS_IsMainThread());
+#ifdef MOZ_WMF_MEDIA_ENGINE
+  // DRM playback via the media engine is disabled, switch back to the state
+  // machine using Gecko's media pipeline.
+  if (GetStateMachine()->IsExternalStateMachine() &&
+      !StaticPrefs::media_wmf_media_engine_drm_playback()) {
+    LOG("Disable external state machine due to DRM playback not allowed");
+    OnPlaybackErrorEvent(
+        MediaResult{NS_ERROR_DOM_MEDIA_EXTERNAL_ENGINE_NOT_SUPPORTED_ERR});
+  }
+#endif
   return GetStateMachine()->SetCDMProxy(aProxy);
 }
 
diff --git a/modules/libpref/init/StaticPrefList.yaml b/modules/libpref/init/StaticPrefList.yaml
index 411da168e1a6..5646f9de4bb6 100644
--- a/modules/libpref/init/StaticPrefList.yaml
+++ b/modules/libpref/init/StaticPrefList.yaml
@@ -10212,6 +10212,12 @@
     value: false
     mirror: always
 
+# This allows playing DRM video via the media engine pipeline.
+-   name: media.wmf.media-engine.drm-playback
+    type: RelaxedAtomicBool
+    value: false
+    mirror: always
+
 # The amount of video raw data the engine stream will queue
 -   name: media.wmf.media-engine.raw-data-threshold.video
     type: RelaxedAtomicInt32