Question E, in the video.
Sir, said that when a speices goes from low oxidation state to high oxidation state then it looses an electron and we put plus sign.
Here in the question of FeC2O4, iron went from +2 to +3 with loss of +1 electron sir has used minus thus showing reverse sing please clear.
file:///Users/niteshchaudhary/Desktop/Screen%20Shot%202018-12-10%20at%209.08.40%20PM.png
In this picture Fe is going from +2 oxidation state to +3 state upon loss of electrons. it is shown correct . sir used negative sign to show charge on electron and not oxidation state.
if still doubt persist ask again.