videos not showing on ipod touch?

i have a 4 gen ipod touch 32 gig. everything is up to date. i was having troubles syncing it with my desktop so i plugged it into my laptop and the syncing went fine. but now if i want to charge it or put some music on i have to hook it up to my desktop (unless i drag my music onto my laptop and drag the laptop itself out every time). now that would be fine but when it hooks up to the laptop i have various movies on it and music as well, when i hook it up to my desktop all those disappear. in itunes it tells me that they are there and i can even watch them on my computer, but on the ipod itself it says that they are not there.

not all of the movies are on the desktop, nor are they all on the laptop. both computers are authorized, and yes the videos are in the right format, i have watched them on there before.

any help would be useful, i don't want to delete my downloaded copies because they were a one time only code so i couldn't redownload them for free again (which is stupidi paid for a digital copy i should be able to download it again if need be)

any help would be useful