The only reasonable way to implement this, would be tagging the checksum (SHA-1) of files as kiddy-safe - through Bitzi or a similar service. The question then is, who should decide what's safe and what isn't. In most countries, a TV series where kids appear in swim suits in an episode (b/c they visit a lake or whatever) wouldn't be an issue. However, there are amish, muslims or just weird people who see sexually abuse into (sic!) everything. Sure you can let the government or perhaps even the UNO decide what's good for your kids and what isn't. Do you want that? Do you really want that? If yes, sorry, then you either don't know what you're saying or I have to despise you.

Now filtering files that contain fvck, svck, pr0n etc. in the title is a nice cute attempt but it's about as safe as crossing a highway with your eyes closed. The industry has failed over and over again to make the internet (or web rather) kiddy-safe. It's not possible (unless you're willing to give up freedom of everyone for your selfish desires). The internet never was, isn't and shall never be safe for kids. As soon as they're old enough, they'll be able to deal with any kind of crap they'll find on the net.

just dont let your kid figure out how to change it

Unless your parents work in the IT business, they probably have far less of a clue about computers then you (as a kid). Even if the kids themselves aren't too bright, it's very likely they have some friends that are.

I really pity those kids that have such parents screaming for control. If you don't have the time to watch and educate your kids, just don't get any. It's not that hard, condoms have been invented. Maybe people should learn about birth control before they scream for parental control.