Hasta La Motion!

i was looking up the tutorial on the Foundry site about using motion estimation within the Furnace_Kronos node.

the shot im doing involves a man as the fg and him running across the screen creating alot of motion blur. im trying to isolate him as a matte so that kronos will know which is the fg and which is the bg so i can do a speed up on the shot seq. do anyone know if when you do fg roto. do you roto the motion blur of the man running across or should i be rotoing to the hard edge?

at the moment i’ve tried both and coming out with different result. neither one being accurate to a good visual state.

thanks
jamie O_o