Anyhow, I have some material I wanted to pull out of the system's main storage. It's not ready to burn to DVD yet, but the drive is close to bursting and I can't wait 'till gaps are filled in. (Things like the two missing episodes of last season's Sleeper Cell.) I had MythBurn build a DVD directory of some episodes and used mplex -f 8 to create DVD-compliant MPEG-2 program streams. But how to verify that they came out right?
OS X ships with an MPEG-2 decoder, along with all the requisite audio decoders (AC3, PCM, DTS.) However, you can't use them outside the DVD Player application. You can pay Apple $20 for a QuickTime component that enables MPEG-2 playback, but it's very particular what it will demultiplex from a program stream and pass on to other decoders. If you try an export from QuickTime Player, you get no audio--the export dialog's settings treat the movie like it has no audio track. It also won't play back anything but MPEG-1 Layer I or II audio. MythBurn is set to always convert audio to AC3 (Dolby Digital). Installing the A52 Codec does not help, since QuickTime won't call it--though I know it works, since playing back the demultiplexed .ac3 file works just great.
The answer, as always, is VLC.