Diagetic and non diegetic sound

                                                         
Non diegetic sound is

Sound whose source is neither visible on the screen nor has been implied to be present in the action:
an example of non diegetic sound

• narrators commentary
•  sound effects which is added for the dramatic effect 
•  mood music

Diagetic is Sound whose source is visible on the screen or whose source is implied to be present by the action of the film,
examples of diegetic sound:

• voices of characters
• sounds made by objects in the story
• music represented as coming from instruments in the story 
  
  In the first 30 seconds of this film it uses non diegtic sound 
  
  https://www.youtube.com/watch?v=H63f7g7ETRI
  
  Diagetic sound is in this film in 2:10 (talking)
  
  https://www.youtube.com/watch?v=0DM8o0IOIR4