Undeletable videos on iPod Classic
On an iPod Classic there is no way to delete them from the device. It needs to be connected to iTunes to do it the official way. The problem will be that it has been so long since your last sync that it may make too many changes to your iPod. You could connect it to iTunes and cancel the sync, then go to the iPod's main page and select to sync manually. At that point you should be able to update the media on your iPod in a more controlled way.