I thought the iplayer streams had stopped using VP6 by default since the 2.0 update? I remember the new bloke in charge making a big deal about moving to H.264

EDIT: Going by this table from beeb hack it looks like flashlow is only used by the wii, which is what I'd expect. But there is another option for broadband streaming using VP6... Maybe that is the issue after all. I thought youtube used the VP6 codec though? I was assuming the issue was the non optimised flash H.264 codec.