.activeSourceBuffers, "removesourcebuffer");
                          sourceBufferAudio.audioTracks[0].enabled = true;
                          sourceBufferVideo.videoTracks[0].selected = false;
                      });

                      test.waitForExpectedEvents(function()
                      {
                          assert_equals(mediaSource.activeSourceBuffers.length, 1,
                            "video source buffer no longer in the activeSourceBuffers list");
                          a