deleted file mode 100644
--- a/testing/web-platform/meta/media-source/mediasource-config-change-webm-a-bitrate.html.ini
+++ /dev/null
@@ -1,3 +0,0 @@
-[mediasource-config-change-webm-a-bitrate.html]
-  type: testharness
-  disabled: https://bugzilla.mozilla.org/show_bug.cgi?id=1066467

deleted file mode 100644
--- a/testing/web-platform/meta/media-source/mediasource-config-change-webm-av-audio-bitrate.html.ini
+++ /dev/null
@@ -1,3 +0,0 @@
-[mediasource-config-change-webm-av-audio-bitrate.html]
-  type: testharness
-  disabled: https://bugzilla.mozilla.org/show_bug.cgi?id=1066467

--- a/testing/web-platform/meta/media-source/mediasource-config-change-webm-av-framesize.html.ini
+++ b/testing/web-platform/meta/media-source/mediasource-config-change-webm-av-framesize.html.ini
@@ -1,3 +1,5 @@
 [mediasource-config-change-webm-av-framesize.html]
   type: testharness
-  disabled: https://bugzilla.mozilla.org/show_bug.cgi?id=1066467
+  [Tests webm frame size changes in multiplexed content.]
+    expected: FAIL
+

deleted file mode 100644
--- a/testing/web-platform/meta/media-source/mediasource-config-change-webm-av-video-bitrate.html.ini
+++ /dev/null
@@ -1,3 +0,0 @@
-[mediasource-config-change-webm-av-video-bitrate.html]
-  type: testharness
-  disabled: https://bugzilla.mozilla.org/show_bug.cgi?id=1066467

--- a/testing/web-platform/meta/media-source/mediasource-config-change-webm-v-bitrate.html.ini
+++ b/testing/web-platform/meta/media-source/mediasource-config-change-webm-v-bitrate.html.ini
@@ -1,3 +1,5 @@
 [mediasource-config-change-webm-v-bitrate.html]
   type: testharness
-  disabled: https://bugzilla.mozilla.org/show_bug.cgi?id=1066467
+  [Tests webm video-only bitrate changes.]
+    expected: FAIL
+

--- a/testing/web-platform/meta/media-source/mediasource-config-change-webm-v-framerate.html.ini
+++ b/testing/web-platform/meta/media-source/mediasource-config-change-webm-v-framerate.html.ini
@@ -1,3 +1,5 @@
 [mediasource-config-change-webm-v-framerate.html]
   type: testharness
-  disabled: https://bugzilla.mozilla.org/show_bug.cgi?id=1066467
+  [Tests webm video-only frame rate changes.]
+    expected: FAIL
+

--- a/testing/web-platform/meta/media-source/mediasource-config-change-webm-v-framesize.html.ini
+++ b/testing/web-platform/meta/media-source/mediasource-config-change-webm-v-framesize.html.ini
@@ -1,3 +1,5 @@
 [mediasource-config-change-webm-v-framesize.html]
   type: testharness
-  disabled: https://bugzilla.mozilla.org/show_bug.cgi?id=1066467
+  [Tests webm video-only frame size changes.]
+    expected: FAIL
+