"Yoiko no minna ha, terebi kara ichi me~to ijou hanarete miru you ni... na?"
"All good children, please watch from more than 1 metre from the TV... okay?"
(Sorry that it's not a great translation, but it's a bit clumsy to translate into English because Japanese is too polite~)
I'm not sure where it comes from, either, but maybe it's a generic warning for Japanese children shows? There was that one incident a few years ago with the Pikachu episode, where someone got a seizure, so maybe they had a law passed about it. (Just like in manuals for video games, how they have a warning for epilepsy.)
......: everything is up at www.strokethebigtree.com/rtl_s_movies