. . . . "On my LG BP-220 deck the thing that trips up the MKV playback is audio codecs it does not know about, mainly Ogg and FLAC. I would not be surprised if it is the same story on the WD device.I have only had trouble with subtitles is on one set of files, a collection of Uresei Yatsura episodes that was encoded when the standard was still a bit in flux." .