Bug#396148: thoggen: only works with dvd source

[Tshepang Lekhonkhobe]

They should be valid unless dvdbackup produces invalid video DVDs; I
don't have access to the PC having the problem at the moment so I
can't post the file list now. Anyway, Totem plays the files as DVD,
complete with menus and all. I'll post the dependencies next time so
that we know which libdvdread version has a problem.

thanks