I doubt that the cpu in the 4G ipod is powerful enough to play video well.  I know for a fact that apple started using a much faster cpu in the 5G so that it could decode mpeg4 and h.264.

I would imagine that even if you got it to play video that it would be jerky and not very enjoyable. 
Mac mini C2D 1.83GHz - 2GB RAM - 200GB 7200rpm HD
Sawtooth w/G4 1GHz - 1GB RAM - SIIG SATA w/2x1TB HD
B&W w/G4 600MHz - 1GB RAM - 2x80GB HD
Sawtooth G4 400MHz - 512MB RAM - 40GB HD
Dell Ultrasharp 2007WFP 20" Widescreen LCD
2.94TB Total Storage