After upgrading to a hacked version 1.1.3 of iPhone firmware, some users experience the inability to use YouTube and despite the many tutorials on the World Wide Web that direct the download and installation of the YouTube activation patch from the AppTap installer, some times it doesn't work.
You will know something is wrong when you see this message shortly after launching the YouTube application on your hacked iPhone: "You must first connect to iTunes with an Internet connection to enable Youtube".
In such a case, the best solution is to manually patch the YouTube certificates on your iPhone.