you manage the ipod touch the same way you would manage your ipod video, meaning you just drag the files and drop them into your movies section in itunes and all you're video's will sync up.
Are the videos formatted in iPod friendly - 640x480 mode?
If not your videos will of course still appear and be playable in iTunes but will not transfer over to your iPod Touch.....
Vanilla
make sure that you check the "sync video" tab when you have the touch plugged in to the computer. I believe by default all of the options other than music are not selected.