Is your 4G full?
Do you really want to watch video?
When you listen to music, what % of the time is your iPod screen where you can see it?
I'm in a similar position. My 4G still has space for music, I'm not that bothered about video - if I need to take it with me, I can stick it on my cellphone, and most of the time, my iPod is in my pocket so I wouldn't even get the benefit of the coloured screen.