You're both fucking morons.
This disposable computing age we're entering has its ups and downs...
1:Create a share on your NAS which has the items you DON'T want them to watch and make it so that it needs a password or whatever credentials you need to connect to it.
2:Add the share to XBMC, but put it under a Master Profile.
3: Create another Profile for your younglings that can't access the shared files. Double bonus, since you password protected the share, if they do go scanning the network, they'll have to have to know the (hopefully) different password to mount the share with your non-kid content.
Check this out: http://forum.xbmc.org/showthread.php?tid=108232 I think it will help you sort your media out with haste.
I've got a sister who's got a BS degree in "Landscape Engineering," she bakes bread for a living.
I've got a sister who's got a BS in Geology and was recently making serious cheddar but the mine closed, so she decided to have a baby and is is out for the duration.
I've got a brother who's a welder, owns some cows, and fancies himself a rancher in progress.
Finally, I've got a brother who thinks that education is something the "man" uses to keep you down.
As for me? Associates degree in business, bachelors degree in general studies in another 18 credits (been doing it in my 'spare' time) and the only one of the lot to have a long-term career, I've been doing computers for 18+ years now. From my experience, the degree doesn't do much but get you in the door for the interview in IT...90% of what I know by heart came from doing it and being a nerd, the other 10% can be determined via Google.