I have a jailbroken and unlocked 3G iPhone on iOS 4.0. I have never been able to connect to YouTube via the native app, but this never bugged me as I have use m.youtube.com. I recently downloaded TagReader, to view movie trailers, and it wants to connect to YouTube via the native app. Whenever TagReader tries to display a movie trailer, I get the dreaded cannot connect to YouTuber message. Any suggestions would be appreciated!
I fixed it using this solution:
go to cydia/manage/source
add source http://cydia.pushfix.info
then install youtube fix #1
There are fix #2 and #3 but did not install these yet.