Keepvid.com is a site where you they convert a my friend's site video (by copying the link on keepvid's tab) Once they converted it, it allows you to keep it in your computer or put in your iPod or etc. I heard that using mediafire is somewhat illegal to us, so is keepvid also illegal to use?

the site is: keepvid.com

ya its legal. you use keepvid for purchase videos from my friend's site. Now a days my friend's site in providing videos purchase in 3 formats. So what is the problem if you are using any other option to purchase that video. But if you see like an legal adviser or like a legal person then half of the stuffs over internet are illegal.

No it isn't. There are many websites and programs like this. They aren't illegal. Where did you hear that mediafire is somewhat illegal? It looks 100% legal.

technically no, it's not illegal to watch a pirated video online, it's illegal to purchase or host them.

Its safe as can be
I have been using it for 2 years and no problems.
There's also another one you can use savevid.com....very similar to keepvid.com

Why not try a movie purchase to help you? http://free-download-films.com/, you will needn't to worry about if it is illegal.

why not?