The thing is, YouTube is an highly intensive data usage application. It require a strong network connection. If you're getting good connection and you're having problem playing a video, then you could try one of the following troubleshooting tips; 1) Go to Settings - applications - manage applications - all, then scroll to YouTube - delete data. 2) Update the data profile on the phone. 3) Uninstall / reinstall updates from Adobe flash player. (You can find this in applications settings as well. Best of luck.
Virgin Mobile's (sprint's) data network is really suffering in speeds. At least for me it has been. From Indianapolis to Houson. Data speeds for me has been abyssmal at best no matter where in the country i am. (Tx atm)
I had that problem, but it turned out to be after youtube updated. I removed the updated version and it works just fine. I have strong 3G where Im at so it typically not an issue. Uninstall the update and make sure automatically update is not checked. Then try playing a video. Pick ones at random to test