avi/mpeg?
Something is seriously flawed with that assumption.
To save as an avi is pretty straightforward unless the audio is in ogg - then you have to demux and reencode the audio into mp3 (get the apropiate codec, Windows/Media Player Update has a nice habit of hobling their own version when updating).
....so don't forget to switch the audio tab into full processing from direct stream copy.
....as for mpeg - virtual dub can't encode into mpeg it wasn't written for that job.
I didn't use -mod that much and I know it was meant to combine the mpeg, ogm, mkv into the original.
However mpg always means a preset combination of audio and video - and probably both streams have to be converted.
