What does pygame.Movie mean by `an MPEG file'?

[Kilian A. Foth]

I just found this amazing video puzzle game written with the pygame
library, which promises to be infinite fun - but I can't get it to
decode any video file I own, except the game's own example .mpg. All I
have is lots and lots of useless .avi, .mp2, .wmv, and so on...

Now, the pygame.Movie documentation says the Movie class can decode
`MPEG movie files'. I know little about multimedia, but I thought
divx/xvid video was a variant of MPEG4, and mp3 audio a variant of 
MPEG1 Layer 3. So obviously, `MPEG movie files' means something more
specific than just `contains MPEG streams'. Does anyone know what
precisely it means? Even better, how should I instruct transcode or
similar programs to re-encode existing files so that Movie objhects
can be created from them?

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