--- a/dom/media/mediasource/ContainerParser.cpp
+++ b/dom/media/mediasource/ContainerParser.cpp
@@ -284,19 +284,21 @@ public:
     }
     aStart = compositionRange.start;
     aEnd = compositionRange.end;
     MSE_DEBUG("MP4ContainerParser(%p)::ParseStartAndEndTimestamps: [%lld, %lld]",
               this, aStart, aEnd);
     return true;
   }
 
+  // Gaps of up to 20ms (marginally longer than a single frame at 60fps) are considered
+  // to be sequential frames.
   int64_t GetRoundingError()
   {
-    return 1000;
+    return 20000;
   }
 
 private:
   nsRefPtr<mp4_demuxer::BufferStream> mStream;
   nsAutoPtr<mp4_demuxer::MoofParser> mParser;
   Monitor mMonitor;
 };