[JonStatt]

When you use the iPhone on Pay and Go with O2, you need to change the data APN to something else.

Unfortunately, it seems this APN blocks the ports required for YouTube to work! Safari works just fine, as do other apps, like Weather and Google Maps....but YouTube sits with the spinning wheel until it times out.

O2 haven't got a clue as they start blaming the phone.....but this is now being reported by several users, and not by those with contract SIMs.