diff --git a/content/media/nsMediaDecoder.cpp b/content/media/nsMediaDecoder.cpp
index ab503e3df31..ea73a476462 100644
--- a/content/media/nsMediaDecoder.cpp
+++ b/content/media/nsMediaDecoder.cpp
@@ -80,6 +80,7 @@ nsMediaDecoder::nsMediaDecoder() :
   mFrameBufferLength(0),
   mPinnedForSeek(PR_FALSE),
   mSizeChanged(PR_FALSE),
+  mImageContainerSizeChanged(PR_FALSE),
   mShuttingDown(PR_FALSE)
 {
   MOZ_COUNT_CTOR(nsMediaDecoder);
@@ -138,9 +139,15 @@ void nsMediaDecoder::Invalidate()
     return;
 
   nsIFrame* frame = mElement->GetPrimaryFrame();
+  PRBool invalidateFrame = PR_FALSE;
 
   {
     nsAutoLock lock(mVideoUpdateLock);
+
+    // Get mImageContainerSizeChanged while holding the lock.
+    invalidateFrame = mImageContainerSizeChanged;
+    mImageContainerSizeChanged = PR_FALSE;
+
     if (mSizeChanged) {
       nsIntSize scaledSize(mRGBWidth, mRGBHeight);
       // Apply the aspect ratio to produce the intrinsic size we report
@@ -169,8 +176,11 @@ void nsMediaDecoder::Invalidate()
 
   if (frame) {
     nsRect contentRect = frame->GetContentRect() - frame->GetPosition();
-    // Only the layer needs to be updated here
-    frame->InvalidateLayer(contentRect, nsDisplayItem::TYPE_VIDEO);
+    if (invalidateFrame) {
+      frame->Invalidate(contentRect);
+    } else {
+      frame->InvalidateLayer(contentRect, nsDisplayItem::TYPE_VIDEO);
+    }
   }
 
 #ifdef MOZ_SVG
@@ -257,7 +267,12 @@ void nsMediaDecoder::SetVideoData(const gfxIntSize& aSize,
     mSizeChanged = PR_TRUE;
   }
   if (mImageContainer && aImage) {
+    gfxIntSize oldFrameSize = mImageContainer->GetCurrentSize();
     mImageContainer->SetCurrentImage(aImage);
+    gfxIntSize newFrameSize = mImageContainer->GetCurrentSize();
+    if (oldFrameSize != newFrameSize) {
+      mImageContainerSizeChanged = PR_TRUE;
+    }
   }
 }
 
diff --git a/content/media/nsMediaDecoder.h b/content/media/nsMediaDecoder.h
index 8ad257352ea..e2e0286fc54 100644
--- a/content/media/nsMediaDecoder.h
+++ b/content/media/nsMediaDecoder.h
@@ -351,9 +351,20 @@ protected:
   // while seeking.
   PRPackedBool mPinnedForSeek;
 
-  // Has our size changed since the last repaint?
+  // Set to PR_TRUE when the video width, height or pixel aspect ratio is
+  // changed by SetVideoData().  The next call to Invalidate() will recalculate
+  // and update the intrinsic size on the element, request a frame reflow and
+  // then reset this flag.
   PRPackedBool mSizeChanged;
 
+  // Set to PR_TRUE in SetVideoData() if the new image has a different size
+  // than the current image.  The image size is also affected by transforms
+  // so this can be true even if mSizeChanged is false, for example when
+  // zooming.  The next call to Invalidate() will call nsIFrame::Invalidate
+  // when this flag is set, rather than just InvalidateLayer, and then reset
+  // this flag.
+  PRPackedBool mImageContainerSizeChanged;
+
   // True if the decoder is being shutdown. At this point all events that
   // are currently queued need to return immediately to prevent javascript
   // being run that operates on the element and decoder during shutdown.