My friend converted some of his DVDs to iPod video format for me and I think he used Videora (not entirely sure). They look and play great but I can't skip through them when I hit forward. The forward function works fine on music and lets me browse the iPod menu so the button's not broken. And, I have some other videos which can be skipped ahead as they should. Why can't I skip some of these videos? Please help, I'm lost.