Google lists eight reasons on its YouTube Community Guidelines page for why it might take down a video. Inciting riots is not among them. But after the White House warned on Tuesday that a crude anti-Muslim movie trailer had sparked lethal violence in the Middle East, Google acted.

Days later, controversy over the 14-minute clip from The Innocence of Muslims was still roiling the Islamic world, with access blocked in Egypt, Libya, India, Indonesia and Afghanistan.

Indonesia

Legal experts and civil libertarians said the controversy highlighted how internet companies, most based in the US, have become global arbiters of free speech, weighing complex issues that traditionally are the province of courts, judges and, occasionally, international treaties.

''Notice that Google has more power over this than either the Egyptian or the US government,'' said Tim Wu, a Columbia University law professor. ''Most free speech today has nothing to do with governments and everything to do with companies.''