This disclosure describes techniques for correcting artifacts that occur along a boundary of a substitute video unit generated using video unit substitution, e.g., motion-compensated video unit interpolation or extrapolation. In accordance with the techniques described in this disclosure, a frame substitution unit identifies first locations within a substitute video unit that correspond with a boundary that exists within a reference video unit and should exist within the substitute video unit, and corrects boundary artifacts in the first locations using a first boundary artifact correction technique. The frame substitution unit also identifies second locations within the substitute video unit that correspond with a boundary that exists within the substitute video unit and does not exist within the reference video unit and corrects boundary artifacts in the second locations using a second boundary artifact correction technique.