Beta 4 is released for iOS6 and the update was missing something according to 9to5mac.
Youtube has been around for iOS late 2007 but now it seems to be the end of it. At first it seemed like it was a bug, but Apple has earlier today confirmed that it will not be in iOS6.

It seems that their license for Youtube has expired Apple points out that one can use Safari or the YouTube app that seems to produce.
However, it seems Youtube remain on the AppleTV which is good for us who do not want to jailbreak our iUnits.