In one embodiment, the method includes selecting a list 0 motion vector of the co-located block in a first reference picture as the motion vector if the co-located block has the list 0 motion vector and a list 1 motion vector. The first reference picture is a type of reference picture permitted to be located temporally before or after the current picture. The method further includes selecting the list 1 motion vector of the co-located block in the first reference picture if the co-located block only has the list 1 motion vector, and deriving at least one motion vector of the bi-predictive block based on the selected motion vector. The deriving includes deriving a first temporal distance from a difference between the current picture and the first reference picture, deriving a second temporal distance from a difference between the first reference picture and a second reference picture, and scaling the selected motion vector based on the first and second temporal distances. The second reference picture is pointed to by the selected motion vector.