Unfortunately, I'm currently unable to fix the pack in our database, because the tool that I use to manage the packs is currently broken. But I'll fix this pack as soon as I'll have fixed the tool.
On the other end, you can fix the pack from your owned videos. Go to that missing movie (it's already in the database) and add it from scratch. When adding it, you'll set the pack name to the name of the pack that already contains the other movies, and that movie will be added to the others.http://www.coollector.com/help.html#packs