It says you'll usually get a superior viewer because it's usually true. 
In this case, the usually-superior viewer has been broken by something, or doesn't like something to do with some of your files.
Something is probably wrong with the Windows Media Player ActiveX Control on your system, and/or your audio codecs and/or the corresponding filetype settings in the registry.
Enable/fix playback of various media formats in Opus has various suggestions if you want to try and fix things.