--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -1497,17 +1497,18 @@ pref("ui.key.menuAccessKeyFocuses", true
 #endif
 
 // Encrypted media extensions.
 pref("media.eme.enabled", true);
 pref("media.eme.apiVisible", true);
 
 // Decode using Gecko Media Plugins in <video>, if a system decoder is not
 // availble and the preferred GMP is available.
-pref("media.gmp.decoder.enabled", true);
+// NOTE: Disabled until Bug 1236756 is fixed by Adobe.
+pref("media.gmp.decoder.enabled", false);
 
 // If decoding-via-GMP is turned on for <video>, use Adobe's GMP for decoding,
 // if it's available. Note: We won't fallback to another GMP if Adobe's is not
 // installed.
 pref("media.gmp.decoder.aac", 2);
 pref("media.gmp.decoder.h264", 2);
 
 // Whether we should run a test-pattern through EME GMPs before assuming they'll