From Yahoo!’s Terms of Service number 19, section E, emphasis theirs:

A SMALL PERCENTAGE OF USERS MAY EXPERIENCE EPILEPTIC SEIZURES WHEN EXPOSED TO CERTAIN LIGHT PATTERNS OR BACKGROUNDS ON A COMPUTER SCREEN OR WHILE USING THE SERVICE. CERTAIN CONDITIONS MAY INDUCE PREVIOUSLY UNDETECTED EPILEPTIC SYMPTOMS EVEN IN USERS WHO HAVE NO HISTORY OF PRIOR SEIZURES OR EPILEPSY.

Finally, Google can now capitalize on Yahoo!’s short comings and capture that elusive epileptic demographic.