Working ok on my Vivacity.
Bizarre thing is though it was stuttering.
So in iplayer settings I lowered it from medium to low and exited app.
Then I opened it up again and changed it back to medium and then it works great!?!?!?!
Mine is not overclocked in anyway on medium setting.You have installed flash on the same page as iplayer on fish n chips RL4 page?
The same lowering and exiting, then going back to medium worked on my brothers Vivacity with a different Rom as well.
The only thing I can think its doing is saving a new config file or something.