If you haven’t got a MPEG-2 decoder installed, you should enable the internal MPEG-2 decoder in Media Player Classic. This usually means that there is a filter missing that is needed to decode playback.exe of the streams in the file. The error message should show some information about the required format, but this information is very cryptic. Below you can find some of the values that the error might show you, together with the format that belongs to it.
The format above is AMR audio. To play this you need to enable AMR in LAV Audio decoder or ffdshow audio decoder. The format above if FPS1 video. To play this you need Fraps.
Or enable Fraps in LAV Video decoder or FPS1 in ffdshow video decoder. PVA source filter in Media Player Classic. The types above usually mean that you are trying to play an incomplete AVI file or a non-standard compliant AVI file. The default AVI splitter of Windows has difficulty to handle incomplete files. Enable the internal AVI splitter in Media Player Classic. The format above is IMA4 audio. Enable Microsoft PCM in LAV Audio decoder or IMA ADPCM in ffdshow audio decoder.
The format above is Ogg Vorbis audio. Enable Vorbis in LAV audio decoder or ffdshow audio decoder. You may get the above error when there is a problem with your graphics driver that prevents the use of DXVA. The solution is to disable hardware acceleration in the video decoder settings. The format above is Indeo 5.
Or enable Indeo in LAV Video decoder. This error means the audio renderer is not accepting the audio input. Usually because of an unsupported sample rate. It can often be fixed by updating your sound driver. Alternatively, you can enable the internal audio renderer in MPC, which is able to resample the audio. You need to disable the internal audio switcher of Media Player Classic.