Loop trouble

Hi I’ve been told I need to do a loop within a loop to achieve what I’m trying to do, but I’m not the most experienced WordPress user and would appreciate a hand.

I’m currently trying to display the most recent posts on my index, which excludes the most recent 5 post from the category videos (ID=12).

I’ve managed to offset the posts by 5, but this offsets the most recent 5 new posts, but not specifically from this category.

Any help or pointers on how to do this would be much appreciared,

Cheers