When using secondary actions it is important that they emphasise the main action rather than take focus away from it. For example if the scene was a character about to suddenly run off screen the character's eyes could stay looking forward, using secondary action the character's eyes may look from side to side. This secondary action could enhance the scene and possibly create an element of anticipation and if successful would enhance the main action, which is the purpose of secondary action.
2:09 in this example the primary action is the mouse putting her arms around her children whilst the secondary action is the facial expressions used on the character. This enhances the primary action.