Nevermind. Ignore my post above. I was editing the wrong server-config.xml file. Apparently, regardless of what drive you install Advanced Server on (mine is installed on the D: drive), the config file is placed on the C: drive in the user's "Application Data" folder.
And, by the way, the correct edit is: . If you have the proper CODEC installed, you can play MKV files, but you cannot FF or Rewind. I set my output bitrate at 8000 Kbps, which gives me visibly better resolution than the default setting.