IPod Classic Sync Problems

Hello

I recently had a rebuild of my PC.
My iPod classic holds loads of music and a large number of videos.
When I connect the Ipod to my PC I get..............

This Ipod is synced with another iTunes Library...........Do you want to erase this iPod and sync with this (I assume the library on my PC) iTunes library...............

The library on my PC appears to hold only the MUSIC on my Ipod and NOT the VIDEOS which are still on my iPod

I do not want to loose the videos.

Help please