diff --git a/dom/media/ipc/RDDParent.cpp b/dom/media/ipc/RDDParent.cpp
index 95702fc5a0f1..9bbd5ae18cb7 100644
--- a/dom/media/ipc/RDDParent.cpp
+++ b/dom/media/ipc/RDDParent.cpp
@@ -10,6 +10,7 @@
 #  include <process.h>
 
 #  include "WMF.h"
+#  include "WMFDecoderModule.h"
 #  include "mozilla/WinDllServices.h"
 #  include "mozilla/gfx/DeviceManagerDx.h"
 #else
@@ -24,6 +25,7 @@
 #include "mozilla/Preferences.h"
 #include "mozilla/RemoteDecoderManagerChild.h"
 #include "mozilla/RemoteDecoderManagerParent.h"
+#include "mozilla/ScopeExit.h"
 #include "mozilla/TimeStamp.h"
 #include "mozilla/dom/MemoryReportRequest.h"
 #include "mozilla/gfx/gfxVars.h"
@@ -151,6 +153,18 @@ mozilla::ipc::IPCResult RDDParent::RecvInit(
 }
 
 IPCResult RDDParent::RecvUpdateVar(const GfxVarUpdate& aUpdate) {
+#if defined(XP_WIN)
+  auto scopeExit = MakeScopeExit(
+      [couldUseHWDecoder = gfx::gfxVars::CanUseHardwareVideoDecoding()] {
+        if (couldUseHWDecoder != gfx::gfxVars::CanUseHardwareVideoDecoding()) {
+          // The capabilities of the system may have changed, force a refresh by
+          // re-initializing the WMF PDM.
+          WMFDecoderModule::Init();
+          Unused << RDDParent::GetSingleton()->SendUpdateMediaCodecsSupported(
+              PDMFactory::Supported(true /* force refresh */));
+        }
+      });
+#endif
   gfxVars::ApplyUpdate(aUpdate);
   return IPC_OK();
 }
diff --git a/dom/media/platforms/PDMFactory.cpp b/dom/media/platforms/PDMFactory.cpp
index 016a1be43098..38d44946fad1 100644
--- a/dom/media/platforms/PDMFactory.cpp
+++ b/dom/media/platforms/PDMFactory.cpp
@@ -618,8 +618,10 @@ void PDMFactory::SetCDMProxy(CDMProxy* aProxy) {
 }
 
 /* static */
-PDMFactory::MediaCodecsSupported PDMFactory::Supported() {
-  static MediaCodecsSupported supported = []() {
+PDMFactory::MediaCodecsSupported PDMFactory::Supported(bool aForceRefresh) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  static auto calculate = []() {
     auto pdm = MakeRefPtr<PDMFactory>();
     MediaCodecsSupported supported;
     // H264 and AAC depends on external framework that must be dynamically
@@ -665,7 +667,11 @@ PDMFactory::MediaCodecsSupported PDMFactory::Supported() {
       supported += MediaCodecs::Wave;
     }
     return supported;
-  }();
+  };
+  static MediaCodecsSupported supported = calculate();
+  if (aForceRefresh) {
+    supported = calculate();
+  }
   return supported;
 }
 
diff --git a/dom/media/platforms/PDMFactory.h b/dom/media/platforms/PDMFactory.h
index 643e571375b2..3194e28d8d57 100644
--- a/dom/media/platforms/PDMFactory.h
+++ b/dom/media/platforms/PDMFactory.h
@@ -87,7 +87,7 @@ class PDMFactory final {
 
   using MediaCodecsSupported = EnumSet<MediaCodecs>;
 
-  static MediaCodecsSupported Supported();
+  static MediaCodecsSupported Supported(bool aForceRefresh = false);
   static bool SupportsMimeType(const nsACString& aMimeType,
                                const MediaCodecsSupported& aSupported);
 
diff --git a/gfx/ipc/GPUParent.cpp b/gfx/ipc/GPUParent.cpp
index f57500388f56..550f51bd42c8 100644
--- a/gfx/ipc/GPUParent.cpp
+++ b/gfx/ipc/GPUParent.cpp
@@ -6,22 +6,32 @@
 
 #ifdef XP_WIN
 #  include "WMF.h"
+#  include "WMFDecoderModule.h"
 #endif
-#include "GPUParent.h"
-#include "gfxConfig.h"
-#include "gfxCrashReporterUtils.h"
-#include "GfxInfoBase.h"
-#include "gfxPlatform.h"
 #include "GLContextProvider.h"
+#include "GPUParent.h"
 #include "GPUProcessHost.h"
 #include "GPUProcessManager.h"
+#include "GfxInfoBase.h"
+#include "ProcessUtils.h"
+#include "VRGPUChild.h"
+#include "VRManager.h"
+#include "VRManagerParent.h"
+#include "VsyncBridgeParent.h"
+#include "cairo.h"
+#include "gfxConfig.h"
+#include "gfxCrashReporterUtils.h"
+#include "gfxPlatform.h"
 #include "mozilla/Assertions.h"
+#include "mozilla/HangDetails.h"
 #include "mozilla/PerfStats.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/RemoteDecoderManagerChild.h"
+#include "mozilla/RemoteDecoderManagerParent.h"
+#include "mozilla/ScopeExit.h"
 #include "mozilla/StaticPrefs_dom.h"
 #include "mozilla/Telemetry.h"
 #include "mozilla/TimeStamp.h"
-#include "mozilla/RemoteDecoderManagerChild.h"
-#include "mozilla/RemoteDecoderManagerParent.h"
 #include "mozilla/dom/MemoryReportRequest.h"
 #include "mozilla/gfx/2D.h"
 #include "mozilla/gfx/gfxVars.h"
@@ -29,43 +39,37 @@
 #include "mozilla/ipc/CrashReporterClient.h"
 #include "mozilla/ipc/ProcessChild.h"
 #include "mozilla/layers/APZInputBridgeParent.h"
-#include "mozilla/layers/APZThreadUtils.h"
 #include "mozilla/layers/APZPublicUtils.h"  // for apz::InitializeGlobalState
+#include "mozilla/layers/APZThreadUtils.h"
 #include "mozilla/layers/CompositorBridgeParent.h"
 #include "mozilla/layers/CompositorManagerParent.h"
 #include "mozilla/layers/CompositorThread.h"
 #include "mozilla/layers/ImageBridgeParent.h"
 #include "mozilla/layers/LayerTreeOwnerTracker.h"
-#include "mozilla/layers/UiCompositorControllerParent.h"
 #include "mozilla/layers/MemoryReportingMLGPU.h"
+#include "mozilla/layers/UiCompositorControllerParent.h"
 #include "mozilla/layers/VideoBridgeParent.h"
 #include "mozilla/webrender/RenderThread.h"
 #include "mozilla/webrender/WebRenderAPI.h"
-#include "mozilla/HangDetails.h"
-#include "mozilla/Preferences.h"
-#include "nscore.h"
 #include "nsDebugImpl.h"
 #include "nsIGfxInfo.h"
 #include "nsThreadManager.h"
+#include "nscore.h"
 #include "prenv.h"
-#include "ProcessUtils.h"
-#include "VRGPUChild.h"
-#include "VRManager.h"
-#include "VRManagerParent.h"
-#include "VsyncBridgeParent.h"
-#include "cairo.h"
 #include "skia/include/core/SkGraphics.h"
 #if defined(XP_WIN)
+#  include <dwrite.h>
+#  include <process.h>
+
+#  include "mozilla/WindowsVersion.h"
 #  include "mozilla/gfx/DeviceManagerDx.h"
 #  include "mozilla/widget/WinCompositorWindowThread.h"
-#  include "mozilla/WindowsVersion.h"
-#  include <process.h>
-#  include <dwrite.h>
 #else
 #  include <unistd.h>
 #endif
 #ifdef MOZ_WIDGET_GTK
 #  include <gtk/gtk.h>
+
 #  include "skia/include/ports/SkTypeface_cairo.h"
 #endif
 #ifdef MOZ_GECKO_PROFILER
@@ -374,6 +378,18 @@ mozilla::ipc::IPCResult GPUParent::RecvInitProfiler(
 }
 
 mozilla::ipc::IPCResult GPUParent::RecvUpdateVar(const GfxVarUpdate& aUpdate) {
+#if defined(XP_WIN)
+  auto scopeExit = MakeScopeExit(
+      [couldUseHWDecoder = gfx::gfxVars::CanUseHardwareVideoDecoding()] {
+        if (couldUseHWDecoder != gfx::gfxVars::CanUseHardwareVideoDecoding()) {
+          // The capabilities of the system may have changed, force a refresh by
+          // re-initializing the WMF PDM.
+          WMFDecoderModule::Init();
+          Unused << GPUParent::GetSingleton()->SendUpdateMediaCodecsSupported(
+              PDMFactory::Supported(true /* force refresh */));
+        }
+      });
+#endif
   gfxVars::ApplyUpdate(aUpdate);
   return IPC_OK();
 }