My new iphone 4 having big problems with youtube..help please

[The Game 161]

For whatever reason when I go onto youtube in 3G coverage the videos are such poor quailty while on wifi the video pic is clear but stops and starts and doesn't work

can somebody explain this to me? is it the phone issue or an update issue?

also i have had problems calling where i can hear the other person fine but they can barely hear me at all...is my iphone faulty?

My old phone the 3G one worked great on youtube..so i don't understand it