TCP optimizer changes some parameters so that YouTube videos load faster from the YouTube application on your device. Install it, restart and you will see how the videos start earlier. It only improves the loading speed under a Wifi network, not on 3G.
Compatible as of iOS 3.1.2.
You can download it free on Cydia in the repo:
http://cydia.pushfix.info/
You need to have done the jailbreak.
I installed it and I think that if it works and in 3g too ... I suppose that "It only improves the loading speed under a Wifi network, not in 3G" with 3g unrestrictor solved, right? ...
It works very well the difference is very noticeable in my case, I have tested it only in wify for now, I recommend it!