After coming to Turkey you will quickly realize that YouTube is inaccessible across the country. Some people have ways to get around the internet restrictions imposed by the government; through proxy servers etc. I do not recommend doing this, as the government keeps a close eye.
However, the YouTube ban is only the beginning of this law. Some 30.000 websites have been banned in Turkey and the internet providers of course comply. Most of the sites that are banned have spoken ill or incorrectly about Ataturk.