Once the control and video tracks have been erased by recording over the original there is no hope of meaningful recovery. Even if there are faint traces of the original in the guard bands there would be no feasable way of recovering the original. Put simply when you record over an existing recording the video recorders rotating head that phyically changes the tapes magnetic pariticles to specific locations. When rerecording on the tape, the Video recorders rotating head moves the magnetic particles to a different location the old recording doesn’t exist anymore.
Digital is different.
