Im on o2 and have an unlimited data plan, the best option is to install the widget which enables you to choose what type of connection you use, of either Dual, 3G, or GSM, and choose 3G only if your in a area which has 3G connectivity available. iplayer will always lag till adobe flash 10 get released, however there is a certain type of tweak you can do, to get iplayer 'just about' functional, and if you want to watch youtube videos I recommend using any of youtube dedicated apps like zoutube. I watch and download vids using zoutube on a 3G and 3.5G connection with no trouble at all.