Spanners, I was writing to a CD-R originally and then changed it to a DVD-RW. I tried drag and drop, copy, and copy and paste and I tried Nero.
And SD I did say above that this is brand new DVD/ROM (bought Saturday last) and loaded with the software that came with it under 'Nero 7 Essentials.' And she runs XP Pro.
I made a new folder with just vids in it thinking this might help.