diff --git a/dom/media/mediaelement/HTMLMediaElement.cpp b/dom/media/mediaelement/HTMLMediaElement.cpp
index 5db7e05ccff..7272c99c7d0 100644
--- a/dom/media/mediaelement/HTMLMediaElement.cpp
+++ b/dom/media/mediaelement/HTMLMediaElement.cpp
@@ -2575,6 +2575,18 @@ nsresult HTMLMediaElement::OnChannelRedirect(nsIChannel* aChannel,
                                              nsIChannel* aNewChannel,
                                              uint32_t aFlags) {
   MOZ_ASSERT(mChannelLoader);
+  if (aNewChannel) {
+    nsCOMPtr<nsIURI> oldURI;
+    if (aChannel) {
+      aChannel->GetURI(getter_AddRefs(oldURI));
+    }
+    aNewChannel->GetURI(getter_AddRefs(mLoadingSrcFinalURI));
+    LOG(LogLevel::Debug,
+        ("{} OnChannelRedirect: from {} to {}", fmt::ptr(this),
+         oldURI ? oldURI->GetSpecOrDefault().get() : "null",
+         mLoadingSrcFinalURI ? mLoadingSrcFinalURI->GetSpecOrDefault().get()
+                             : "null"));
+  }
   return mChannelLoader->Redirect(aChannel, aNewChannel, aFlags);
 }
 
@@ -2617,6 +2629,8 @@ void HTMLMediaElement::AbortExistingLoads() {
     mChannelLoader = nullptr;
   }
 
+  mLoadingSrcFinalURI = nullptr;
+
   bool fireTimeUpdate = false;
 
   if (mDecoder) {
@@ -2731,12 +2745,12 @@ void HTMLMediaElement::NoSupportedMediaSourceError(
 
   bool isSameOriginLoad = false;
   nsresult rv = NS_ERROR_NOT_AVAILABLE;
-  if (mSrcAttrTriggeringPrincipal && mLoadingSrc) {
-    rv = mSrcAttrTriggeringPrincipal->IsSameOrigin(mLoadingSrc,
-                                                   &isSameOriginLoad);
+  if (mLoadingSrcTriggeringPrincipal && mLoadingSrcFinalURI) {
+    rv = mLoadingSrcTriggeringPrincipal->IsSameOrigin(mLoadingSrcFinalURI,
+                                                      &isSameOriginLoad);
   }
 
-  if (NS_SUCCEEDED(rv) && !isSameOriginLoad) {
+  if (NS_FAILED(rv) || !isSameOriginLoad) {
     // aErrorDetails can include sensitive details like MimeType or HTTP Status
     // Code. In case we're loading a 3rd party resource we should not leak this
     // and pass a Generic Error Message
@@ -2968,6 +2982,7 @@ void HTMLMediaElement::SelectResource(
       } else {
         mLoadingSrc = nullptr;
       }
+      mLoadingSrcFinalURI = mLoadingSrc;
       mLoadingSrcTriggeringPrincipal = mSrcAttrTriggeringPrincipal;
       DDLOG(DDLogCategory::Property, "loading_src",
             nsCString(NS_ConvertUTF16toUTF8(src)));
@@ -3255,6 +3270,7 @@ void HTMLMediaElement::LoadFromSourceChildren(
 
     RemoveMediaElementFromURITable();
     mLoadingSrc = uri;
+    mLoadingSrcFinalURI = mLoadingSrc;
     mLoadingSrcTriggeringPrincipal = child->GetSrcTriggeringPrincipal();
     DDLOG(DDLogCategory::Property, "loading_src",
           nsCString(NS_ConvertUTF16toUTF8(src)));
diff --git a/dom/media/mediaelement/HTMLMediaElement.h b/dom/media/mediaelement/HTMLMediaElement.h
index e0e0d3658af..163b2151b23 100644
--- a/dom/media/mediaelement/HTMLMediaElement.h
+++ b/dom/media/mediaelement/HTMLMediaElement.h
@@ -1646,6 +1646,12 @@ class HTMLMediaElement : public nsGenericHTMLElement,
   // redirects etc.
   nsCOMPtr<nsIURI> mLoadingSrc;
 
+  // The URI of the resource actually loaded. Starts equal to mLoadingSrc and
+  // is updated to the post-redirect URI on each redirect. Used to decide
+  // cross-origin load-error redaction; null means we have no captured URI, and
+  // is treated as cross-origin.
+  nsCOMPtr<nsIURI> mLoadingSrcFinalURI;
+
   // The triggering principal for the current source.
   nsCOMPtr<nsIPrincipal> mLoadingSrcTriggeringPrincipal;